€•.Œsphinx.addnodes”Œdocument”“”)”}”(Œ rawsource”Œ”Œchildren”]”(Œ translations”Œ LanguagesNode”“”)”}”(hhh]”(hŒ pending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ refdomain”Œstd”Œreftype”Œdoc”Œ reftarget”Œ4/translations/zh_CN/admin-guide/device-mapper/dm-log”Œmodname”NŒ classname”NŒ refexplicit”ˆuŒtagname”hhh ubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ4/translations/zh_TW/admin-guide/device-mapper/dm-log”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ4/translations/it_IT/admin-guide/device-mapper/dm-log”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ4/translations/ja_JP/admin-guide/device-mapper/dm-log”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ4/translations/ko_KR/admin-guide/device-mapper/dm-log”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ refdomain”h)Œreftype”h+Œ reftarget”Œ4/translations/sp_SP/admin-guide/device-mapper/dm-log”Œmodname”NŒ classname”NŒ refexplicit”ˆuh1hhh ubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h hhŒ _document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒDevice-Mapper Logging”h]”hŒDevice-Mapper Logging”…””}”(hh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒN/var/lib/git/docbuild/linux/Documentation/admin-guide/device-mapper/dm-log.rst”h KubhŒ paragraph”“”)”}”(hXZThe device-mapper logging code is used by some of the device-mapper RAID targets to track regions of the disk that are not consistent. A region (or portion of the address space) of the disk may be inconsistent because a RAID stripe is currently being operated on or a machine died while the region was being altered. In the case of mirrors, a region would be considered dirty/inconsistent while you are writing to it because the writes need to be replicated for all the legs of the mirror and may not reach the legs at the same time. Once all writes are complete, the region is considered clean again.”h]”hXZThe device-mapper logging code is used by some of the device-mapper RAID targets to track regions of the disk that are not consistent. A region (or portion of the address space) of the disk may be inconsistent because a RAID stripe is currently being operated on or a machine died while the region was being altered. In the case of mirrors, a region would be considered dirty/inconsistent while you are writing to it because the writes need to be replicated for all the legs of the mirror and may not reach the legs at the same time. Once all writes are complete, the region is considered clean again.”…””}”(hh¹hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hXThere is a generic logging interface that the device-mapper RAID implementations use to perform logging operations (see dm_dirty_log_type in include/linux/dm-dirty-log.h). Various different logging implementations are available and provide different capabilities. The list includes:”h]”hXThere is a generic logging interface that the device-mapper RAID implementations use to perform logging operations (see dm_dirty_log_type in include/linux/dm-dirty-log.h). Various different logging implementations are available and provide different capabilities. The list includes:”…””}”(hhÇhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubhŒtable”“”)”}”(hhh]”hŒtgroup”“”)”}”(hhh]”(hŒcolspec”“”)”}”(hhh]”h}”(h]”h ]”h"]”h$]”h&]”Œcolwidth”Kuh1hßhhÜubhà)”}”(hhh]”h}”(h]”h ]”h"]”h$]”h&]”Œcolwidth”K>uh1hßhhÜubhŒthead”“”)”}”(hhh]”hŒrow”“”)”}”(hhh]”(hŒentry”“”)”}”(hhh]”h¸)”}”(hŒType”h]”hŒType”…””}”(hjhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khjubah}”(h]”h ]”h"]”h$]”h&]”uh1hÿhhüubj)”}”(hhh]”h¸)”}”(hŒFiles”h]”hŒFiles”…””}”(hjhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khjubah}”(h]”h ]”h"]”h$]”h&]”uh1hÿhhüubeh}”(h]”h ]”h"]”h$]”h&]”uh1húhh÷ubah}”(h]”h ]”h"]”h$]”h&]”uh1hõhhÜubhŒtbody”“”)”}”(hhh]”(hû)”}”(hhh]”(j)”}”(hhh]”h¸)”}”(hŒdisk”h]”hŒdisk”…””}”(hjFhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhjCubah}”(h]”h ]”h"]”h$]”h&]”uh1hÿhj@ubj)”}”(hhh]”h¸)”}”(hŒdrivers/md/dm-log.c”h]”hŒdrivers/md/dm-log.c”…””}”(hj]hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhjZubah}”(h]”h ]”h"]”h$]”h&]”uh1hÿhj@ubeh}”(h]”h ]”h"]”h$]”h&]”uh1húhj=ubhû)”}”(hhh]”(j)”}”(hhh]”h¸)”}”(hŒcore”h]”hŒcore”…””}”(hj}hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khjzubah}”(h]”h ]”h"]”h$]”h&]”uh1hÿhjwubj)”}”(hhh]”h¸)”}”(hŒdrivers/md/dm-log.c”h]”hŒdrivers/md/dm-log.c”…””}”(hj”hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj‘ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÿhjwubeh}”(h]”h ]”h"]”h$]”h&]”uh1húhj=ubhû)”}”(hhh]”(j)”}”(hhh]”h¸)”}”(hŒ userspace”h]”hŒ userspace”…””}”(hj´hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj±ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÿhj®ubj)”}”(hhh]”h¸)”}”(hŒ=drivers/md/dm-log-userspace* include/linux/dm-log-userspace.h”h]”hŒ=drivers/md/dm-log-userspace* include/linux/dm-log-userspace.h”…””}”(hjËhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhjÈubah}”(h]”h ]”h"]”h$]”h&]”uh1hÿhj®ubeh}”(h]”h ]”h"]”h$]”h&]”uh1húhj=ubeh}”(h]”h ]”h"]”h$]”h&]”uh1j;hhÜubeh}”(h]”h ]”h"]”h$]”h&]”Œcols”Kuh1hÚhh×ubah}”(h]”h ]”h"]”h$]”h&]”uh1hÕhh£hžhhŸh¶h Nubh¢)”}”(hhh]”(h§)”}”(hŒThe "disk" log type”h]”hŒThe “disk†log type”…””}”(hjûhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hjøhžhhŸh¶h Kubh¸)”}”(hŒmThis log implementation commits the log state to disk. This way, the logging state survives reboots/crashes.”h]”hŒmThis log implementation commits the log state to disk. This way, the logging state survives reboots/crashes.”…””}”(hj hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khjøhžhubeh}”(h]”Œthe-disk-log-type”ah ]”h"]”Œthe "disk" log type”ah$]”h&]”uh1h¡hh£hžhhŸh¶h Kubh¢)”}”(hhh]”(h§)”}”(hŒThe "core" log type”h]”hŒThe “core†log type”…””}”(hj"hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hjhžhhŸh¶h K"ubh¸)”}”(hŒïThis log implementation keeps the log state in memory. The log state will not survive a reboot or crash, but there may be a small boost in performance. This method can also be used if no storage device is available for storing log state.”h]”hŒïThis log implementation keeps the log state in memory. The log state will not survive a reboot or crash, but there may be a small boost in performance. This method can also be used if no storage device is available for storing log state.”…””}”(hj0hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K#hjhžhubeh}”(h]”Œthe-core-log-type”ah ]”h"]”Œthe "core" log type”ah$]”h&]”uh1h¡hh£hžhhŸh¶h K"ubh¢)”}”(hhh]”(h§)”}”(hŒThe "userspace" log type”h]”hŒThe “userspace†log type”…””}”(hjIhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hjFhžhhŸh¶h K)ubh¸)”}”(hŒäThis log type simply provides a way to export the log API to userspace, so log implementations can be done there. This is done by forwarding most logging requests to userspace, where a daemon receives and processes the request.”h]”hŒäThis log type simply provides a way to export the log API to userspace, so log implementations can be done there. This is done by forwarding most logging requests to userspace, where a daemon receives and processes the request.”…””}”(hjWhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K*hjFhžhubh¸)”}”(hXThe structure used for communication between kernel and userspace are located in include/linux/dm-log-userspace.h. Due to the frequency, diversity, and 2-way communication nature of the exchanges between kernel and userspace, 'connector' is used as the interface for communication.”h]”hXThe structure used for communication between kernel and userspace are located in include/linux/dm-log-userspace.h. Due to the frequency, diversity, and 2-way communication nature of the exchanges between kernel and userspace, ‘connector’ is used as the interface for communication.”…””}”(hjehžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K/hjFhžhubh¸)”}”(hX=There are currently two userspace log implementations that leverage this framework - "clustered-disk" and "clustered-core". These implementations provide a cluster-coherent log for shared-storage. Device-mapper mirroring can be used in a shared-storage environment when the cluster log implementations are employed.”h]”hXEThere are currently two userspace log implementations that leverage this framework - “clustered-disk†and “clustered-coreâ€. These implementations provide a cluster-coherent log for shared-storage. 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