€•äè      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ1/translations/zh_CN/admin-guide/device-mapper/vdo”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/zh_TW/admin-guide/device-mapper/vdo”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/it_IT/admin-guide/device-mapper/vdo”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/ja_JP/admin-guide/device-mapper/vdo”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/ko_KR/admin-guide/device-mapper/vdo”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ1/translations/sp_SP/admin-guide/device-mapper/vdo”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒcomment”“”)”}”(hŒ%SPDX-License-Identifier: GPL-2.0-only”h]”hŒ%SPDX-License-Identifier: GPL-2.0-only”…””}”hh£sbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1h¡hhhžhhŸŒK/var/lib/git/docbuild/linux/Documentation/admin-guide/device-mapper/vdo.rst”h KubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒdm-vdo”h]”hŒdm-vdo”…””}”(hh»hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hh¶hžhhŸh³h KubhŒ	paragraph”“”)”}”(hX¸  The dm-vdo (virtual data optimizer) device mapper target provides
block-level deduplication, compression, and thin provisioning. As a device
mapper target, it can add these features to the storage stack, compatible
with any file system. The vdo target does not protect against data
corruption, relying instead on integrity protection of the storage below
it. It is strongly recommended that lvm be used to manage vdo volumes. See
lvmvdo(7).”h]”hX¸  The dm-vdo (virtual data optimizer) device mapper target provides
block-level deduplication, compression, and thin provisioning. As a device
mapper target, it can add these features to the storage stack, compatible
with any file system. The vdo target does not protect against data
corruption, relying instead on integrity protection of the storage below
it. It is strongly recommended that lvm be used to manage vdo volumes. See
lvmvdo(7).”…””}”(hhËhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Khh¶hžhubeh}”(h]”Œdm-vdo”ah ]”h"]”Œdm-vdo”ah$]”h&]”uh1h´hhhžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒUserspace component”h]”hŒUserspace component”…””}”(hhähžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hháhžhhŸh³h KubhÊ)”}”(hŒOFormatting a vdo volume requires the use of the 'vdoformat' tool, available
at:”h]”hŒSFormatting a vdo volume requires the use of the â€˜vdoformatâ€™ tool, available
at:”…””}”(hhòhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KhháhžhubhÊ)”}”(hŒhttps://github.com/dm-vdo/vdo/”h]”hŒ	reference”“”)”}”(hj  h]”hŒhttps://github.com/dm-vdo/vdo/”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”j  uh1j  hj   ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KhháhžhubhÊ)”}”(hXÇ  In most cases, a vdo target will recover from a crash automatically the
next time it is started. In cases where it encountered an unrecoverable
error (either during normal operation or crash recovery) the target will
enter or come up in read-only mode. Because read-only mode is indicative of
data-loss, a positive action must be taken to bring vdo out of read-only
mode. The 'vdoforcerebuild' tool, available from the same repo, is used to
prepare a read-only vdo to exit read-only mode. After running this tool,
the vdo target will rebuild its metadata the next time it is
started. Although some data may be lost, the rebuilt vdo's metadata will be
internally consistent and the target will be writable again.”h]”hXÍ  In most cases, a vdo target will recover from a crash automatically the
next time it is started. In cases where it encountered an unrecoverable
error (either during normal operation or crash recovery) the target will
enter or come up in read-only mode. Because read-only mode is indicative of
data-loss, a positive action must be taken to bring vdo out of read-only
mode. The â€˜vdoforcerebuildâ€™ tool, available from the same repo, is used to
prepare a read-only vdo to exit read-only mode. After running this tool,
the vdo target will rebuild its metadata the next time it is
started. Although some data may be lost, the rebuilt vdoâ€™s metadata will be
internally consistent and the target will be writable again.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KhháhžhubhÊ)”}”(hŒ·The repo also contains additional userspace tools which can be used to
inspect a vdo target's on-disk metadata. Fortunately, these tools are
rarely needed except by dm-vdo developers.”h]”hŒ¹The repo also contains additional userspace tools which can be used to
inspect a vdo targetâ€™s on-disk metadata. Fortunately, these tools are
rarely needed except by dm-vdo developers.”…””}”(hj(  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K!hháhžhubeh}”(h]”Œuserspace-component”ah ]”h"]”Œuserspace component”ah$]”h&]”uh1h´hhhžhhŸh³h Kubhµ)”}”(hhh]”(hº)”}”(hŒMetadata requirements”h]”hŒMetadata requirements”…””}”(hjA  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj>  hžhhŸh³h K&ubhÊ)”}”(hXW  Each vdo volume reserves 3GB of space for metadata, or more depending on
its configuration. It is helpful to check that the space saved by
deduplication and compression is not cancelled out by the metadata
requirements. An estimation of the space saved for a specific dataset can
be computed with the vdo estimator tool, which is available at:”h]”hXW  Each vdo volume reserves 3GB of space for metadata, or more depending on
its configuration. It is helpful to check that the space saved by
deduplication and compression is not cancelled out by the metadata
requirements. An estimation of the space saved for a specific dataset can
be computed with the vdo estimator tool, which is available at:”…””}”(hjO  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K(hj>  hžhubhÊ)”}”(hŒ'https://github.com/dm-vdo/vdoestimator/”h]”j  )”}”(hj_  h]”hŒ'https://github.com/dm-vdo/vdoestimator/”…””}”(hja  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”j_  uh1j  hj]  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K.hj>  hžhubeh}”(h]”Œmetadata-requirements”ah ]”h"]”Œmetadata requirements”ah$]”h&]”uh1h´hhhžhhŸh³h K&ubhµ)”}”(hhh]”(hº)”}”(hŒTarget interface”h]”hŒTarget interface”…””}”(hj€  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj}  hžhhŸh³h K1ubhµ)”}”(hhh]”(hº)”}”(hŒ
Table line”h]”hŒ
Table line”…””}”(hj‘  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjŽ  hžhhŸh³h K4ubhŒliteral_block”“”)”}”(hŒ¢<offset> <logical device size> vdo V4 <storage device>
<storage device size> <minimum I/O size> <block map cache size>
<block map era length> [optional arguments]”h]”hŒ¢<offset> <logical device size> vdo V4 <storage device>
<storage device size> <minimum I/O size> <block map cache size>
<block map era length> [optional arguments]”…””}”hj¡  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h K8hjŽ  hžhubhÊ)”}”(hŒRequired parameters:”h]”hŒRequired parameters:”…””}”(hj¯  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K=hjŽ  hžhubhŒblock_quote”“”)”}”(hX-  offset:
        The offset, in sectors, at which the vdo volume's logical
        space begins.

logical device size:
        The size of the device which the vdo volume will service,
        in sectors. Must match the current logical size of the vdo
        volume.

storage device:
        The device holding the vdo volume's data and metadata.

storage device size:
        The size of the device holding the vdo volume, as a number
        of 4096-byte blocks. Must match the current size of the vdo
        volume.

minimum I/O size:
        The minimum I/O size for this vdo volume to accept, in
        bytes. Valid values are 512 or 4096. The recommended value
        is 4096.

block map cache size:
        The size of the block map cache, as a number of 4096-byte
        blocks. The minimum and recommended value is 32768 blocks.
        If the logical thread count is non-zero, the cache size
        must be at least 4096 blocks per logical thread.

block map era length:
        The speed with which the block map cache writes out
        modified block map pages. A smaller era length is likely to
        reduce the amount of time spent rebuilding, at the cost of
        increased block map writes during normal operation. The
        maximum and recommended value is 16380; the minimum value
        is 1.
”h]”hŒdefinition_list”“”)”}”(hhh]”(hŒdefinition_list_item”“”)”}”(hŒPoffset:
The offset, in sectors, at which the vdo volume's logical
space begins.
”h]”(hŒterm”“”)”}”(hŒoffset:”h]”hŒoffset:”…””}”(hjÐ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h KAhjÊ  ubhŒ
definition”“”)”}”(hhh]”hÊ)”}”(hŒGThe offset, in sectors, at which the vdo volume's logical
space begins.”h]”hŒIThe offset, in sectors, at which the vdo volumeâ€™s logical
space begins.”…””}”(hjã  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K@hjà  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjÊ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h KAhjÅ  ubjÉ  )”}”(hŒ’logical device size:
The size of the device which the vdo volume will service,
in sectors. Must match the current logical size of the vdo
volume.
”h]”(jÏ  )”}”(hŒlogical device size:”h]”hŒlogical device size:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h KFhjý  ubjß  )”}”(hhh]”hÊ)”}”(hŒ|The size of the device which the vdo volume will service,
in sectors. Must match the current logical size of the vdo
volume.”h]”hŒ|The size of the device which the vdo volume will service,
in sectors. Must match the current logical size of the vdo
volume.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KDhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjý  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h KFhjÅ  ubjÉ  )”}”(hŒGstorage device:
The device holding the vdo volume's data and metadata.
”h]”(jÏ  )”}”(hŒstorage device:”h]”hŒstorage device:”…””}”(hj0  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h KIhj,  ubjß  )”}”(hhh]”hÊ)”}”(hŒ6The device holding the vdo volume's data and metadata.”h]”hŒ8The device holding the vdo volumeâ€™s data and metadata.”…””}”(hjA  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KIhj>  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj,  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h KIhjÅ  ubjÉ  )”}”(hŒ”storage device size:
The size of the device holding the vdo volume, as a number
of 4096-byte blocks. Must match the current size of the vdo
volume.
”h]”(jÏ  )”}”(hŒstorage device size:”h]”hŒstorage device size:”…””}”(hj_  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h KNhj[  ubjß  )”}”(hhh]”hÊ)”}”(hŒ~The size of the device holding the vdo volume, as a number
of 4096-byte blocks. Must match the current size of the vdo
volume.”h]”hŒ~The size of the device holding the vdo volume, as a number
of 4096-byte blocks. Must match the current size of the vdo
volume.”…””}”(hjp  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KLhjm  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj[  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h KNhjÅ  ubjÉ  )”}”(hŒminimum I/O size:
The minimum I/O size for this vdo volume to accept, in
bytes. Valid values are 512 or 4096. The recommended value
is 4096.
”h]”(jÏ  )”}”(hŒminimum I/O size:”h]”hŒminimum I/O size:”…””}”(hjŽ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h KShjŠ  ubjß  )”}”(hhh]”hÊ)”}”(hŒzThe minimum I/O size for this vdo volume to accept, in
bytes. Valid values are 512 or 4096. The recommended value
is 4096.”h]”hŒzThe minimum I/O size for this vdo volume to accept, in
bytes. Valid values are 512 or 4096. The recommended value
is 4096.”…””}”(hjŸ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KQhjœ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjŠ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h KShjÅ  ubjÉ  )”}”(hŒôblock map cache size:
The size of the block map cache, as a number of 4096-byte
blocks. The minimum and recommended value is 32768 blocks.
If the logical thread count is non-zero, the cache size
must be at least 4096 blocks per logical thread.
”h]”(jÏ  )”}”(hŒblock map cache size:”h]”hŒblock map cache size:”…””}”(hj½  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h KYhj¹  ubjß  )”}”(hhh]”hÊ)”}”(hŒÝThe size of the block map cache, as a number of 4096-byte
blocks. The minimum and recommended value is 32768 blocks.
If the logical thread count is non-zero, the cache size
must be at least 4096 blocks per logical thread.”h]”hŒÝThe size of the block map cache, as a number of 4096-byte
blocks. The minimum and recommended value is 32768 blocks.
If the logical thread count is non-zero, the cache size
must be at least 4096 blocks per logical thread.”…””}”(hjÎ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KVhjË  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj¹  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h KYhjÅ  ubjÉ  )”}”(hX9  block map era length:
The speed with which the block map cache writes out
modified block map pages. A smaller era length is likely to
reduce the amount of time spent rebuilding, at the cost of
increased block map writes during normal operation. The
maximum and recommended value is 16380; the minimum value
is 1.
”h]”(jÏ  )”}”(hŒblock map era length:”h]”hŒblock map era length:”…””}”(hjì  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h Kahjè  ubjß  )”}”(hhh]”hÊ)”}”(hX"  The speed with which the block map cache writes out
modified block map pages. A smaller era length is likely to
reduce the amount of time spent rebuilding, at the cost of
increased block map writes during normal operation. The
maximum and recommended value is 16380; the minimum value
is 1.”h]”hX"  The speed with which the block map cache writes out
modified block map pages. A smaller era length is likely to
reduce the amount of time spent rebuilding, at the cost of
increased block map writes during normal operation. The
maximum and recommended value is 16380; the minimum value
is 1.”…””}”(hjý  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K\hjú  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjè  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h KahjÅ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÃ  hj¿  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j½  hŸh³h K?hjŽ  hžhubeh}”(h]”Œ
table-line”ah ]”h"]”Œ
table line”ah$]”h&]”uh1h´hj}  hžhhŸh³h K4ubhµ)”}”(hhh]”(hº)”}”(hŒOptional parameters:”h]”hŒOptional parameters:”…””}”(hj.  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj+  hžhhŸh³h KdubhÊ)”}”(hŒHSome or all of these parameters may be specified as <key> <value> pairs.”h]”hŒHSome or all of these parameters may be specified as <key> <value> pairs.”…””}”(hj<  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kehj+  hžhubhÊ)”}”(hŒThread related parameters:”h]”hŒThread related parameters:”…””}”(hjJ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kghj+  hžhubhÊ)”}”(hŒŠDifferent categories of work are assigned to separate thread groups, and
the number of threads in each group can be configured separately.”h]”hŒŠDifferent categories of work are assigned to separate thread groups, and
the number of threads in each group can be configured separately.”…””}”(hjX  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kihj+  hžhubhÊ)”}”(hŒÈIf <hash>, <logical>, and <physical> are all set to 0, the work handled by
all three thread types will be handled by a single thread. If any of these
values are non-zero, all of them must be non-zero.”h]”hŒÈIf <hash>, <logical>, and <physical> are all set to 0, the work handled by
all three thread types will be handled by a single thread. If any of these
values are non-zero, all of them must be non-zero.”…””}”(hjf  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Klhj+  hžhubj¾  )”}”(hXî  ack:
        The number of threads used to complete bios. Since
        completing a bio calls an arbitrary completion function
        outside the vdo volume, threads of this type allow the vdo
        volume to continue processing requests even when bio
        completion is slow. The default is 1.

bio:
        The number of threads used to issue bios to the underlying
        storage. Threads of this type allow the vdo volume to
        continue processing requests even when bio submission is
        slow. The default is 4.

bioRotationInterval:
        The number of bios to enqueue on each bio thread before
        switching to the next thread. The value must be greater
        than 0 and not more than 1024; the default is 64.

cpu:
        The number of threads used to do CPU-intensive work, such
        as hashing and compression. The default is 1.

hash:
        The number of threads used to manage data comparisons for
        deduplication based on the hash value of data blocks. The
        default is 0.

logical:
        The number of threads used to manage caching and locking
        based on the logical address of incoming bios. The default
        is 0; the maximum is 60.

physical:
        The number of threads used to manage administration of the
        underlying storage device. At format time, a slab size for
        the vdo is chosen; the vdo storage device must be large
        enough to have at least 1 slab per physical thread. The
        default is 0; the maximum is 16.
”h]”jÄ  )”}”(hhh]”(jÉ  )”}”(hX  ack:
The number of threads used to complete bios. Since
completing a bio calls an arbitrary completion function
outside the vdo volume, threads of this type allow the vdo
volume to continue processing requests even when bio
completion is slow. The default is 1.
”h]”(jÏ  )”}”(hŒack:”h]”hŒack:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h Kuhj{  ubjß  )”}”(hhh]”hÊ)”}”(hX   The number of threads used to complete bios. Since
completing a bio calls an arbitrary completion function
outside the vdo volume, threads of this type allow the vdo
volume to continue processing requests even when bio
completion is slow. The default is 1.”h]”hX   The number of threads used to complete bios. Since
completing a bio calls an arbitrary completion function
outside the vdo volume, threads of this type allow the vdo
volume to continue processing requests even when bio
completion is slow. The default is 1.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kqhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj{  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h Kuhjx  ubjÉ  )”}”(hŒÇbio:
The number of threads used to issue bios to the underlying
storage. Threads of this type allow the vdo volume to
continue processing requests even when bio submission is
slow. The default is 4.
”h]”(jÏ  )”}”(hŒbio:”h]”hŒbio:”…””}”(hj®  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h K{hjª  ubjß  )”}”(hhh]”hÊ)”}”(hŒÁThe number of threads used to issue bios to the underlying
storage. Threads of this type allow the vdo volume to
continue processing requests even when bio submission is
slow. The default is 4.”h]”hŒÁThe number of threads used to issue bios to the underlying
storage. Threads of this type allow the vdo volume to
continue processing requests even when bio submission is
slow. The default is 4.”…””}”(hj¿  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kxhj¼  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjª  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h K{hjx  ubjÉ  )”}”(hŒ·bioRotationInterval:
The number of bios to enqueue on each bio thread before
switching to the next thread. The value must be greater
than 0 and not more than 1024; the default is 64.
”h]”(jÏ  )”}”(hŒbioRotationInterval:”h]”hŒbioRotationInterval:”…””}”(hjÝ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h K€hjÙ  ubjß  )”}”(hhh]”hÊ)”}”(hŒ¡The number of bios to enqueue on each bio thread before
switching to the next thread. The value must be greater
than 0 and not more than 1024; the default is 64.”h]”hŒ¡The number of bios to enqueue on each bio thread before
switching to the next thread. The value must be greater
than 0 and not more than 1024; the default is 64.”…””}”(hjî  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K~hjë  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjÙ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h K€hjx  ubjÉ  )”}”(hŒmcpu:
The number of threads used to do CPU-intensive work, such
as hashing and compression. The default is 1.
”h]”(jÏ  )”}”(hŒcpu:”h]”hŒcpu:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h K„hj  ubjß  )”}”(hhh]”hÊ)”}”(hŒgThe number of threads used to do CPU-intensive work, such
as hashing and compression. The default is 1.”h]”hŒgThe number of threads used to do CPU-intensive work, such
as hashing and compression. The default is 1.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kƒhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h K„hjx  ubjÉ  )”}”(hŒˆhash:
The number of threads used to manage data comparisons for
deduplication based on the hash value of data blocks. The
default is 0.
”h]”(jÏ  )”}”(hŒhash:”h]”hŒhash:”…””}”(hj;  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h K‰hj7  ubjß  )”}”(hhh]”hÊ)”}”(hŒThe number of threads used to manage data comparisons for
deduplication based on the hash value of data blocks. The
default is 0.”h]”hŒThe number of threads used to manage data comparisons for
deduplication based on the hash value of data blocks. The
default is 0.”…””}”(hjL  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K‡hjI  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj7  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h K‰hjx  ubjÉ  )”}”(hŒ–logical:
The number of threads used to manage caching and locking
based on the logical address of incoming bios. The default
is 0; the maximum is 60.
”h]”(jÏ  )”}”(hŒlogical:”h]”hŒlogical:”…””}”(hjj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h KŽhjf  ubjß  )”}”(hhh]”hÊ)”}”(hŒŒThe number of threads used to manage caching and locking
based on the logical address of incoming bios. The default
is 0; the maximum is 60.”h]”hŒŒThe number of threads used to manage caching and locking
based on the logical address of incoming bios. The default
is 0; the maximum is 60.”…””}”(hj{  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KŒhjx  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjf  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h KŽhjx  ubjÉ  )”}”(hX  physical:
The number of threads used to manage administration of the
underlying storage device. At format time, a slab size for
the vdo is chosen; the vdo storage device must be large
enough to have at least 1 slab per physical thread. The
default is 0; the maximum is 16.
”h]”(jÏ  )”}”(hŒ	physical:”h]”hŒ	physical:”…””}”(hj™  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h K•hj•  ubjß  )”}”(hhh]”hÊ)”}”(hX  The number of threads used to manage administration of the
underlying storage device. At format time, a slab size for
the vdo is chosen; the vdo storage device must be large
enough to have at least 1 slab per physical thread. The
default is 0; the maximum is 16.”h]”hX  The number of threads used to manage administration of the
underlying storage device. At format time, a slab size for
the vdo is chosen; the vdo storage device must be large
enough to have at least 1 slab per physical thread. The
default is 0; the maximum is 16.”…””}”(hjª  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K‘hj§  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj•  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h K•hjx  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÃ  hjt  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j½  hŸh³h Kphj+  hžhubhÊ)”}”(hŒMiscellaneous parameters:”h]”hŒMiscellaneous parameters:”…””}”(hjÐ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K—hj+  hžhubj¾  )”}”(hXv  maxDiscard:
        The maximum size of discard bio accepted, in 4096-byte
        blocks. I/O requests to a vdo volume are normally split
        into 4096-byte blocks, and processed up to 2048 at a time.
        However, discard requests to a vdo volume can be
        automatically split to a larger size, up to <maxDiscard>
        4096-byte blocks in a single bio, and are limited to 1500
        at a time. Increasing this value may provide better overall
        performance, at the cost of increased latency for the
        individual discard requests. The default and minimum is 1;
        the maximum is UINT_MAX / 4096.

deduplication:
        Whether deduplication is enabled. The default is 'on'; the
        acceptable values are 'on' and 'off'.

compression:
        Whether compression is enabled. The default is 'off'; the
        acceptable values are 'on' and 'off'.
”h]”jÄ  )”}”(hhh]”(jÉ  )”}”(hX'  maxDiscard:
The maximum size of discard bio accepted, in 4096-byte
blocks. I/O requests to a vdo volume are normally split
into 4096-byte blocks, and processed up to 2048 at a time.
However, discard requests to a vdo volume can be
automatically split to a larger size, up to <maxDiscard>
4096-byte blocks in a single bio, and are limited to 1500
at a time. Increasing this value may provide better overall
performance, at the cost of increased latency for the
individual discard requests. The default and minimum is 1;
the maximum is UINT_MAX / 4096.
”h]”(jÏ  )”}”(hŒmaxDiscard:”h]”hŒmaxDiscard:”…””}”(hjé  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h K£hjå  ubjß  )”}”(hhh]”hÊ)”}”(hX  The maximum size of discard bio accepted, in 4096-byte
blocks. I/O requests to a vdo volume are normally split
into 4096-byte blocks, and processed up to 2048 at a time.
However, discard requests to a vdo volume can be
automatically split to a larger size, up to <maxDiscard>
4096-byte blocks in a single bio, and are limited to 1500
at a time. Increasing this value may provide better overall
performance, at the cost of increased latency for the
individual discard requests. The default and minimum is 1;
the maximum is UINT_MAX / 4096.”h]”hX  The maximum size of discard bio accepted, in 4096-byte
blocks. I/O requests to a vdo volume are normally split
into 4096-byte blocks, and processed up to 2048 at a time.
However, discard requests to a vdo volume can be
automatically split to a larger size, up to <maxDiscard>
4096-byte blocks in a single bio, and are limited to 1500
at a time. Increasing this value may provide better overall
performance, at the cost of increased latency for the
individual discard requests. The default and minimum is 1;
the maximum is UINT_MAX / 4096.”…””}”(hjú  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kšhj÷  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjå  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h K£hjâ  ubjÉ  )”}”(hŒpdeduplication:
Whether deduplication is enabled. The default is 'on'; the
acceptable values are 'on' and 'off'.
”h]”(jÏ  )”}”(hŒdeduplication:”h]”hŒdeduplication:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h K§hj  ubjß  )”}”(hhh]”hÊ)”}”(hŒ`Whether deduplication is enabled. The default is 'on'; the
acceptable values are 'on' and 'off'.”h]”hŒlWhether deduplication is enabled. The default is â€˜onâ€™; the
acceptable values are â€˜onâ€™ and â€˜offâ€™.”…””}”(hj)  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K¦hj&  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h K§hjâ  ubjÉ  )”}”(hŒmcompression:
Whether compression is enabled. The default is 'off'; the
acceptable values are 'on' and 'off'.
”h]”(jÏ  )”}”(hŒcompression:”h]”hŒcompression:”…””}”(hjG  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h K«hjC  ubjß  )”}”(hhh]”hÊ)”}”(hŒ_Whether compression is enabled. The default is 'off'; the
acceptable values are 'on' and 'off'.”h]”hŒkWhether compression is enabled. The default is â€˜offâ€™; the
acceptable values are â€˜onâ€™ and â€˜offâ€™.”…””}”(hjX  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KªhjU  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjC  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h K«hjâ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÃ  hjÞ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j½  hŸh³h K™hj+  hžhubeh}”(h]”Œoptional-parameters”ah ]”h"]”Œoptional parameters:”ah$]”h&]”uh1h´hj}  hžhhŸh³h Kdubhµ)”}”(hhh]”(hº)”}”(hŒDevice modification”h]”hŒDevice modification”…””}”(hj‰  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj†  hžhhŸh³h K®ubhÊ)”}”(hX  A modified table may be loaded into a running, non-suspended vdo volume.
The modifications will take effect when the device is next resumed. The
modifiable parameters are <logical device size>, <physical device size>,
<maxDiscard>, <compression>, and <deduplication>.”h]”hX  A modified table may be loaded into a running, non-suspended vdo volume.
The modifications will take effect when the device is next resumed. The
modifiable parameters are <logical device size>, <physical device size>,
<maxDiscard>, <compression>, and <deduplication>.”…””}”(hj—  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K°hj†  hžhubhÊ)”}”(hXe  If the logical device size or physical device size are changed, upon
successful resume vdo will store the new values and require them on future
startups. These two parameters may not be decreased. The logical device
size may not exceed 4 PB. The physical device size must increase by at
least 32832 4096-byte blocks if at all, and must not exceed the size of the
underlying storage device. Additionally, when formatting the vdo device, a
slab size is chosen: the physical device size may never increase above the
size which provides 8192 slabs, and each increase must be large enough to
add at least one new slab.”h]”hXe  If the logical device size or physical device size are changed, upon
successful resume vdo will store the new values and require them on future
startups. These two parameters may not be decreased. The logical device
size may not exceed 4 PB. The physical device size must increase by at
least 32832 4096-byte blocks if at all, and must not exceed the size of the
underlying storage device. Additionally, when formatting the vdo device, a
slab size is chosen: the physical device size may never increase above the
size which provides 8192 slabs, and each increase must be large enough to
add at least one new slab.”…””}”(hj¥  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kµhj†  hžhubhÊ)”}”(hŒ	Examples:”h]”hŒ	Examples:”…””}”(hj³  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K¿hj†  hžhubhÊ)”}”(hŒStart a previously-formatted vdo volume with 1 GB logical space and 1 GB
physical space, storing to /dev/dm-1 which has more than 1 GB of space.”h]”hŒStart a previously-formatted vdo volume with 1 GB logical space and 1 GB
physical space, storing to /dev/dm-1 which has more than 1 GB of space.”…””}”(hjÁ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KÁhj†  hžhubj   )”}”(hŒRdmsetup create vdo0 --table \
"0 2097152 vdo V4 /dev/dm-1 262144 4096 32768 16380"”h]”hŒRdmsetup create vdo0 --table \
"0 2097152 vdo V4 /dev/dm-1 262144 4096 32768 16380"”…””}”hjÏ  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h KÆhj†  hžhubhÊ)”}”(hŒGrow the logical size to 4 GB.”h]”hŒGrow the logical size to 4 GB.”…””}”(hjÝ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KÉhj†  hžhubj   )”}”(hŒfdmsetup reload vdo0 --table \
"0 8388608 vdo V4 /dev/dm-1 262144 4096 32768 16380"
dmsetup resume vdo0”h]”hŒfdmsetup reload vdo0 --table \
"0 8388608 vdo V4 /dev/dm-1 262144 4096 32768 16380"
dmsetup resume vdo0”…””}”hjë  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h KÍhj†  hžhubhÊ)”}”(hŒGrow the physical size to 2 GB.”h]”hŒGrow the physical size to 2 GB.”…””}”(hjù  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KÑhj†  hžhubj   )”}”(hŒfdmsetup reload vdo0 --table \
"0 8388608 vdo V4 /dev/dm-1 524288 4096 32768 16380"
dmsetup resume vdo0”h]”hŒfdmsetup reload vdo0 --table \
"0 8388608 vdo V4 /dev/dm-1 524288 4096 32768 16380"
dmsetup resume vdo0”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h KÕhj†  hžhubhÊ)”}”(hŒEGrow the physical size by 1 GB more and increase max discard sectors.”h]”hŒEGrow the physical size by 1 GB more and increase max discard sectors.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KÙhj†  hžhubj   )”}”(hŒtdmsetup reload vdo0 --table \
"0 10485760 vdo V4 /dev/dm-1 786432 4096 32768 16380 maxDiscard 8"
dmsetup resume vdo0”h]”hŒtdmsetup reload vdo0 --table \
"0 10485760 vdo V4 /dev/dm-1 786432 4096 32768 16380 maxDiscard 8"
dmsetup resume vdo0”…””}”hj#  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h KÝhj†  hžhubhÊ)”}”(hŒStop the vdo volume.”h]”hŒStop the vdo volume.”…””}”(hj1  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Káhj†  hžhubj   )”}”(hŒdmsetup remove vdo0”h]”hŒdmsetup remove vdo0”…””}”hj?  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h Kåhj†  hžhubhÊ)”}”(hŒ~Start the vdo volume again. Note that the logical and physical device sizes
must still match, but other parameters can change.”h]”hŒ~Start the vdo volume again. Note that the logical and physical device sizes
must still match, but other parameters can change.”…””}”(hjM  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kçhj†  hžhubj   )”}”(hŒmdmsetup create vdo1 --table \
"0 10485760 vdo V4 /dev/dm-1 786432 512 65550 5000 hash 1 logical 3 physical 2"”h]”hŒmdmsetup create vdo1 --table \
"0 10485760 vdo V4 /dev/dm-1 786432 512 65550 5000 hash 1 logical 3 physical 2"”…””}”hj[  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h Kìhj†  hžhubeh}”(h]”Œdevice-modification”ah ]”h"]”Œdevice modification”ah$]”h&]”uh1h´hj}  hžhhŸh³h K®ubhµ)”}”(hhh]”(hº)”}”(hŒMessages”h]”hŒMessages”…””}”(hjt  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjq  hžhhŸh³h KðubhÊ)”}”(hŒ,All vdo devices accept messages in the form:”h]”hŒ,All vdo devices accept messages in the form:”…””}”(hj‚  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kñhjq  hžhubj   )”}”(hŒCdmsetup message <target-name> 0 <message-name> <message-parameters>”h]”hŒCdmsetup message <target-name> 0 <message-name> <message-parameters>”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h Kõhjq  hžhubhÊ)”}”(hŒThe messages are:”h]”hŒThe messages are:”…””}”(hjž  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h K÷hjq  hžhubj¾  )”}”(hX  stats:
        Outputs the current view of the vdo statistics. Mostly used
        by the vdostats userspace program to interpret the output
        buffer.

config:
        Outputs useful vdo configuration information. Mostly used
        by users who want to recreate a similar VDO volume and
        want to know the creation configuration used.

dump:
        Dumps many internal structures to the system log. This is
        not always safe to run, so it should only be used to debug
        a hung vdo. Optional parameters to specify structures to
        dump are:

                viopool: The pool of I/O requests incoming bios
                pools: A synonym of 'viopool'
                vdo: Most of the structures managing on-disk data
                queues: Basic information about each vdo thread
                threads: A synonym of 'queues'
                default: Equivalent to 'queues vdo'
                all: All of the above.

dump-on-shutdown:
        Perform a default dump next time vdo shuts down.

”h]”jÄ  )”}”(hhh]”(jÉ  )”}”(hŒ…stats:
Outputs the current view of the vdo statistics. Mostly used
by the vdostats userspace program to interpret the output
buffer.
”h]”(jÏ  )”}”(hŒstats:”h]”hŒstats:”…””}”(hj·  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h Kühj³  ubjß  )”}”(hhh]”hÊ)”}”(hŒ}Outputs the current view of the vdo statistics. Mostly used
by the vdostats userspace program to interpret the output
buffer.”h]”hŒ}Outputs the current view of the vdo statistics. Mostly used
by the vdostats userspace program to interpret the output
buffer.”…””}”(hjÈ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h KúhjÅ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj³  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h Kühj°  ubjÉ  )”}”(hŒ§config:
Outputs useful vdo configuration information. Mostly used
by users who want to recreate a similar VDO volume and
want to know the creation configuration used.
”h]”(jÏ  )”}”(hŒconfig:”h]”hŒconfig:”…””}”(hjæ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h Mhjâ  ubjß  )”}”(hhh]”hÊ)”}”(hŒžOutputs useful vdo configuration information. Mostly used
by users who want to recreate a similar VDO volume and
want to know the creation configuration used.”h]”hŒžOutputs useful vdo configuration information. Mostly used
by users who want to recreate a similar VDO volume and
want to know the creation configuration used.”…””}”(hj÷  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Kÿhjô  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjâ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h Mhj°  ubjÉ  )”}”(hX  dump:
Dumps many internal structures to the system log. This is
not always safe to run, so it should only be used to debug
a hung vdo. Optional parameters to specify structures to
dump are:

        viopool: The pool of I/O requests incoming bios
        pools: A synonym of 'viopool'
        vdo: Most of the structures managing on-disk data
        queues: Basic information about each vdo thread
        threads: A synonym of 'queues'
        default: Equivalent to 'queues vdo'
        all: All of the above.
”h]”(jÏ  )”}”(hŒdump:”h]”hŒdump:”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h Mhj  ubjß  )”}”(hhh]”(hÊ)”}”(hŒ·Dumps many internal structures to the system log. This is
not always safe to run, so it should only be used to debug
a hung vdo. Optional parameters to specify structures to
dump are:”h]”hŒ·Dumps many internal structures to the system log. This is
not always safe to run, so it should only be used to debug
a hung vdo. Optional parameters to specify structures to
dump are:”…””}”(hj&  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Mhj#  ubj¾  )”}”(hX
  viopool: The pool of I/O requests incoming bios
pools: A synonym of 'viopool'
vdo: Most of the structures managing on-disk data
queues: Basic information about each vdo thread
threads: A synonym of 'queues'
default: Equivalent to 'queues vdo'
all: All of the above.
”h]”hÊ)”}”(hX	  viopool: The pool of I/O requests incoming bios
pools: A synonym of 'viopool'
vdo: Most of the structures managing on-disk data
queues: Basic information about each vdo thread
threads: A synonym of 'queues'
default: Equivalent to 'queues vdo'
all: All of the above.”h]”hX  viopool: The pool of I/O requests incoming bios
pools: A synonym of â€˜viopoolâ€™
vdo: Most of the structures managing on-disk data
queues: Basic information about each vdo thread
threads: A synonym of â€˜queuesâ€™
default: Equivalent to â€˜queues vdoâ€™
all: All of the above.”…””}”(hj8  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h M	hj4  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j½  hŸh³h M	hj#  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h Mhj°  ubjÉ  )”}”(hŒDdump-on-shutdown:
Perform a default dump next time vdo shuts down.

”h]”(jÏ  )”}”(hŒdump-on-shutdown:”h]”hŒdump-on-shutdown:”…””}”(hj\  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÎ  hŸh³h MhjX  ubjß  )”}”(hhh]”hÊ)”}”(hŒ0Perform a default dump next time vdo shuts down.”h]”hŒ0Perform a default dump next time vdo shuts down.”…””}”(hjm  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Mhjj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jÞ  hjX  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÈ  hŸh³h Mhj°  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jÃ  hj¬  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j½  hŸh³h Kùhjq  hžhubeh}”(h]”Œmessages”ah ]”h"]”Œmessages”ah$]”h&]”uh1h´hj}  hžhhŸh³h Kðubhµ)”}”(hhh]”(hº)”}”(hŒStatus”h]”hŒStatus”…””}”(hjž  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj›  hžhhŸh³h Mubj   )”}”(hX‘  <device> <operating mode> <in recovery> <index state>
<compression state> <physical blocks used> <total physical blocks>

    device:
            The name of the vdo volume.

    operating mode:
            The current operating mode of the vdo volume; values may be
            'normal', 'recovering' (the volume has detected an issue
            with its metadata and is attempting to repair itself), and
            'read-only' (an error has occurred that forces the vdo
            volume to only support read operations and not writes).

    in recovery:
            Whether the vdo volume is currently in recovery mode;
            values may be 'recovering' or '-' which indicates not
            recovering.

    index state:
            The current state of the deduplication index in the vdo
            volume; values may be 'closed', 'closing', 'error',
            'offline', 'online', 'opening', and 'unknown'.

    compression state:
            The current state of compression in the vdo volume; values
            may be 'offline' and 'online'.

    used physical blocks:
            The number of physical blocks in use by the vdo volume.

    total physical blocks:
            The total number of physical blocks the vdo volume may use;
            the difference between this value and the
            <used physical blocks> is the number of blocks the vdo
            volume has left before being full.”h]”hX‘  <device> <operating mode> <in recovery> <index state>
<compression state> <physical blocks used> <total physical blocks>

    device:
            The name of the vdo volume.

    operating mode:
            The current operating mode of the vdo volume; values may be
            'normal', 'recovering' (the volume has detected an issue
            with its metadata and is attempting to repair itself), and
            'read-only' (an error has occurred that forces the vdo
            volume to only support read operations and not writes).

    in recovery:
            Whether the vdo volume is currently in recovery mode;
            values may be 'recovering' or '-' which indicates not
            recovering.

    index state:
            The current state of the deduplication index in the vdo
            volume; values may be 'closed', 'closing', 'error',
            'offline', 'online', 'opening', and 'unknown'.

    compression state:
            The current state of compression in the vdo volume; values
            may be 'offline' and 'online'.

    used physical blocks:
            The number of physical blocks in use by the vdo volume.

    total physical blocks:
            The total number of physical blocks the vdo volume may use;
            the difference between this value and the
            <used physical blocks> is the number of blocks the vdo
            volume has left before being full.”…””}”hj¬  sbah}”(h]”h ]”h"]”h$]”h&]”h±h²uh1jŸ  hŸh³h Mhj›  hžhubeh}”(h]”Œstatus”ah ]”h"]”Œstatus”ah$]”h&]”uh1h´hj}  hžhhŸh³h Mubeh}”(h]”Œtarget-interface”ah ]”h"]”Œtarget interface”ah$]”h&]”uh1h´hhhžhhŸh³h K1ubhµ)”}”(hhh]”(hº)”}”(hŒMemory Requirements”h]”hŒMemory Requirements”…””}”(hjÍ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjÊ  hžhhŸh³h M?ubhÊ)”}”(hŒgA vdo target requires a fixed 38 MB of RAM along with the following amounts
that scale with the target:”h]”hŒgA vdo target requires a fixed 38 MB of RAM along with the following amounts
that scale with the target:”…””}”(hjÛ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h MAhjÊ  hžhubhŒbullet_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒr1.15 MB of RAM for each 1 MB of configured block map cache size. The
block map cache requires a minimum of 150 MB.”h]”hÊ)”}”(hŒr1.15 MB of RAM for each 1 MB of configured block map cache size. The
block map cache requires a minimum of 150 MB.”h]”hŒr1.15 MB of RAM for each 1 MB of configured block map cache size. The
block map cache requires a minimum of 150 MB.”…””}”(hjô  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h MDhjð  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjë  hžhhŸh³h Nubjï  )”}”(hŒ-1.6 MB of RAM for each 1 TB of logical space.”h]”hÊ)”}”(hj
  h]”hŒ-1.6 MB of RAM for each 1 TB of logical space.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h MFhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjë  hžhhŸh³h Nubjï  )”}”(hŒG268 MB of RAM for each 1 TB of physical storage managed by the volume.
”h]”hÊ)”}”(hŒF268 MB of RAM for each 1 TB of physical storage managed by the volume.”h]”hŒF268 MB of RAM for each 1 TB of physical storage managed by the volume.”…””}”(hj#  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h MGhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hjë  hžhhŸh³h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ-”uh1jé  hŸh³h MDhjÊ  hžhubhÊ)”}”(hXM  The deduplication index requires additional memory which scales with the
size of the deduplication window. For dense indexes, the index requires 1
GB of RAM per 1 TB of window. For sparse indexes, the index requires 1 GB
of RAM per 10 TB of window. The index configuration is set when the target
is formatted and may not be modified.”h]”hXM  The deduplication index requires additional memory which scales with the
size of the deduplication window. For dense indexes, the index requires 1
GB of RAM per 1 TB of window. For sparse indexes, the index requires 1 GB
of RAM per 10 TB of window. The index configuration is set when the target
is formatted and may not be modified.”…””}”(hj?  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h MIhjÊ  hžhubeh}”(h]”Œmemory-requirements”ah ]”h"]”Œmemory requirements”ah$]”h&]”uh1h´hhhžhhŸh³h M?ubhµ)”}”(hhh]”(hº)”}”(hŒModule Parameters”h]”hŒModule Parameters”…””}”(hjX  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hjU  hžhhŸh³h MPubhÊ)”}”(hŒ®The vdo driver has a numeric parameter 'log_level' which controls the
verbosity of logging from the driver. The default setting is 6
(LOGLEVEL_INFO and more severe messages).”h]”hŒ²The vdo driver has a numeric parameter â€˜log_levelâ€™ which controls the
verbosity of logging from the driver. The default setting is 6
(LOGLEVEL_INFO and more severe messages).”…””}”(hjf  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h MRhjU  hžhubeh}”(h]”Œmodule-parameters”ah ]”h"]”Œmodule parameters”ah$]”h&]”uh1h´hhhžhhŸh³h MPubhµ)”}”(hhh]”(hº)”}”(hŒRun-time Usage”h]”hŒRun-time Usage”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj|  hžhhŸh³h MWubhÊ)”}”(hŒtWhen using dm-vdo, it is important to be aware of the ways in which its
behavior differs from other storage targets.”h]”hŒtWhen using dm-vdo, it is important to be aware of the ways in which its
behavior differs from other storage targets.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h MYhj|  hžhubjê  )”}”(hhh]”(jï  )”}”(hŒÛThere is no guarantee that over-writes of existing blocks will succeed.
Because the underlying storage may be multiply referenced, over-writing
an existing block generally requires a vdo to have a free block
available.
”h]”hÊ)”}”(hŒÚThere is no guarantee that over-writes of existing blocks will succeed.
Because the underlying storage may be multiply referenced, over-writing
an existing block generally requires a vdo to have a free block
available.”h]”hŒÚThere is no guarantee that over-writes of existing blocks will succeed.
Because the underlying storage may be multiply referenced, over-writing
an existing block generally requires a vdo to have a free block
available.”…””}”(hj¢  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h M\hjž  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj›  hžhhŸh³h Nubjï  )”}”(hXx  When blocks are no longer in use, sending a discard request for those
blocks lets the vdo release references for those blocks. If the vdo is
thinly provisioned, discarding unused blocks is essential to prevent the
target from running out of space. However, due to the sharing of
duplicate blocks, no discard request for any given logical block is
guaranteed to reclaim space.
”h]”hÊ)”}”(hXw  When blocks are no longer in use, sending a discard request for those
blocks lets the vdo release references for those blocks. If the vdo is
thinly provisioned, discarding unused blocks is essential to prevent the
target from running out of space. However, due to the sharing of
duplicate blocks, no discard request for any given logical block is
guaranteed to reclaim space.”h]”hXw  When blocks are no longer in use, sending a discard request for those
blocks lets the vdo release references for those blocks. If the vdo is
thinly provisioned, discarding unused blocks is essential to prevent the
target from running out of space. However, due to the sharing of
duplicate blocks, no discard request for any given logical block is
guaranteed to reclaim space.”…””}”(hjº  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Mahj¶  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj›  hžhhŸh³h Nubjï  )”}”(hŒ¦Assuming the underlying storage properly implements flush requests, vdo
is resilient against crashes, however, unflushed writes may or may not
persist after a crash.
”h]”hÊ)”}”(hŒ¥Assuming the underlying storage properly implements flush requests, vdo
is resilient against crashes, however, unflushed writes may or may not
persist after a crash.”h]”hŒ¥Assuming the underlying storage properly implements flush requests, vdo
is resilient against crashes, however, unflushed writes may or may not
persist after a crash.”…””}”(hjÒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h MhhjÎ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj›  hžhhŸh³h Nubjï  )”}”(hŒéEach write to a vdo target entails a significant amount of processing.
However, much of the work is paralellizable. Therefore, vdo targets
achieve better throughput at higher I/O depths, and can support up 2048
requests in parallel.
”h]”hÊ)”}”(hŒèEach write to a vdo target entails a significant amount of processing.
However, much of the work is paralellizable. Therefore, vdo targets
achieve better throughput at higher I/O depths, and can support up 2048
requests in parallel.”h]”hŒèEach write to a vdo target entails a significant amount of processing.
However, much of the work is paralellizable. Therefore, vdo targets
achieve better throughput at higher I/O depths, and can support up 2048
requests in parallel.”…””}”(hjê  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Mlhjæ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jî  hj›  hžhhŸh³h Nubeh}”(h]”h ]”h"]”h$]”h&]”j=  j>  uh1jé  hŸh³h M\hj|  hžhubeh}”(h]”Œrun-time-usage”ah ]”h"]”Œrun-time usage”ah$]”h&]”uh1h´hhhžhhŸh³h MWubhµ)”}”(hhh]”(hº)”}”(hŒTuning”h]”hŒTuning”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¹hj	  hžhhŸh³h MrubhÊ)”}”(hX·  The vdo device has many options, and it can be difficult to make optimal
choices without perfect knowledge of the workload. Additionally, most
configuration options must be set when a vdo target is started, and cannot
be changed without shutting it down completely; the configuration cannot be
changed while the target is active. Ideally, tuning with simulated
workloads should be performed before deploying vdo in production
environments.”h]”hX·  The vdo device has many options, and it can be difficult to make optimal
choices without perfect knowledge of the workload. Additionally, most
configuration options must be set when a vdo target is started, and cannot
be changed without shutting it down completely; the configuration cannot be
changed while the target is active. Ideally, tuning with simulated
workloads should be performed before deploying vdo in production
environments.”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Mthj	  hžhubhÊ)”}”(hXå  The most important value to adjust is the block map cache size. In order to
service a request for any logical address, a vdo must load the portion of
the block map which holds the relevant mapping. These mappings are cached.
Performance will suffer when the working set does not fit in the cache. By
default, a vdo allocates 128 MB of metadata cache in RAM to support
efficient access to 100 GB of logical space at a time. It should be scaled
up proportionally for larger working sets.”h]”hXå  The most important value to adjust is the block map cache size. In order to
service a request for any logical address, a vdo must load the portion of
the block map which holds the relevant mapping. These mappings are cached.
Performance will suffer when the working set does not fit in the cache. By
default, a vdo allocates 128 MB of metadata cache in RAM to support
efficient access to 100 GB of logical space at a time. It should be scaled
up proportionally for larger working sets.”…””}”(hj+	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h M|hj	  hžhubhÊ)”}”(hX  The logical and physical thread counts should also be adjusted. A logical
thread controls a disjoint section of the block map, so additional logical
threads increase parallelism and can increase throughput. Physical threads
control a disjoint section of the data blocks, so additional physical
threads can also increase throughput. However, excess threads can waste
resources and increase contention.”h]”hX  The logical and physical thread counts should also be adjusted. A logical
thread controls a disjoint section of the block map, so additional logical
threads increase parallelism and can increase throughput. Physical threads
control a disjoint section of the data blocks, so additional physical
threads can also increase throughput. However, excess threads can waste
resources and increase contention.”…””}”(hj9	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h M„hj	  hžhubhÊ)”}”(hX	  Bio submission threads control the parallelism involved in sending I/O to
the underlying storage; fewer threads mean there is more opportunity to
reorder I/O requests for performance benefit, but also that each I/O
request has to wait longer before being submitted.”h]”hX	  Bio submission threads control the parallelism involved in sending I/O to
the underlying storage; fewer threads mean there is more opportunity to
reorder I/O requests for performance benefit, but also that each I/O
request has to wait longer before being submitted.”…””}”(hjG	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h M‹hj	  hžhubhÊ)”}”(hXD  Bio acknowledgment threads are used for finishing I/O requests. This is
done on dedicated threads since the amount of work required to execute a
bio's callback can not be controlled by the vdo itself. Usually one thread
is sufficient but additional threads may be beneficial, particularly when
bios have CPU-heavy callbacks.”h]”hXF  Bio acknowledgment threads are used for finishing I/O requests. This is
done on dedicated threads since the amount of work required to execute a
bioâ€™s callback can not be controlled by the vdo itself. Usually one thread
is sufficient but additional threads may be beneficial, particularly when
bios have CPU-heavy callbacks.”…””}”(hjU	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h Mhj	  hžhubhÊ)”}”(hŒŠCPU threads are used for hashing and for compression; in workloads with
compression enabled, more threads may result in higher throughput.”h]”hŒŠCPU threads are used for hashing and for compression; in workloads with
compression enabled, more threads may result in higher throughput.”…””}”(hjc	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h M–hj	  hžhubhÊ)”}”(hŒõHash threads are used to sort active requests by hash and determine whether
they should deduplicate; the most CPU intensive actions done by these
threads are comparison of 4096-byte data blocks. In most cases, a single
hash thread is sufficient.”h]”hŒõHash threads are used to sort active requests by hash and determine whether
they should deduplicate; the most CPU intensive actions done by these
threads are comparison of 4096-byte data blocks. In most cases, a single
hash thread is sufficient.”…””}”(hjq	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÉhŸh³h M™hj	  hžhubeh}”(h]”Œtuning”ah ]”h"]”Œtuning”ah$]”h&]”uh1h´hhhžhhŸh³h Mrubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h³uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¹NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”jª	  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h³Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(hÞhÛj;  j8  jz  jw  jÇ  jÄ  j(  j%  jƒ  j€  jn  jk  j˜  j•  j¿  j¼  jR  jO  jy  jv  j		  j	  j„	  j	  uŒ	nametypes”}”(hÞ‰j;  ‰jz  ‰jÇ  ‰j(  ‰jƒ  ‰jn  ‰j˜  ‰j¿  ‰jR  ‰jy  ‰j		  ‰j„	  ‰uh}”(hÛh¶j8  hájw  j>  jÄ  j}  j%  jŽ  j€  j+  jk  j†  j•  jq  j¼  j›  jO  jÊ  jv  jU  j	  j|  j	  j	  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.