**mdadm** is a utility used to create and manage **software RAID** devices implemented through
**Multiple devices driver (MD)** in kernel. It supports following RAID metadata formats:

* [Linux native RAID](https://raid.wiki.kernel.org/index.php/RAID_superblock_formats):

  Known as **native** or **native RAID**. First and default metadata format. Metadata management
  is implemented in **MD driver**.

* Matrix Storage Manager Support (no reference, metadata format documentation is proprietary).

  Known as **IMSM**. Metadata format developed and maintained by **Intel®** as a part of **VROC**
  solution. There are some functional differences between **native** and **imsm**. The most
  important difference is that the metadata is managed from userspace.

  **CAUTION:** **imsm** is compatible with **Intel RST**, however it is not officially supported.
  You are using it on your own risk.

* [Common RAID DDF Specification Revision](https://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf)

    **IMPORTANT:** DDF is in **maintenance only** mode. There is no active development around it.
    Please do not use it in new solutions.

# Questions and Support

This Github site is **not** right place to ask if your are looking for:
- support from Linux Raid Community;
- support with kernel issues;

This is the place where development of mdadm application is done. Please, do not use for
looking for support. You should always ask on [Mailing List](https://lore.kernel.org/linux-raid/).

Please use issues if you have confirmation that issue you are experiencing is related to mdadm
components:
- mdadm;
- mdmon;
- raid6check;
- swap_super;
- test_stripe;
- systemd services ( see systemd/);
- udev rules;
- manual pages (including md.man)

For example:
- mdadm issues (e.g segfaults, memory leaks, crashes, bad communication with MD driver);
- feature requests for mdadm;
- suggestions or minor fixes requested (e.g. better error messages);

Generally, if you are not sure it is better to ask on
[Mailing List](https://lore.kernel.org/linux-raid/) first.

# How to Contribute

Effective immediately [Github](https://github.com/md-raid-utilities/mdadm) is the primary
location for **mdadm**. Use pull request to contribute.

It was originally hosted on [kernel.org](https://kernel.org/). You can access the old repository
[here](https://git.kernel.org/pub/scm/utils/mdadm/mdadm.git).

Patches sent through Mailing list are accepted but Github is preferred. Sent then to ML only
if you cannot use Github. Please add "mdadm:" to the subject to allow automation to create Github
Pull Request and run checks.

**NOTE:** Maintainers may ask you to send RFC to mailing list if the proposed code requires
consultation with kernel developers.

Kernel coding style is used. Please familiarize with general kernel
[submitting patches](https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html)
documentation. Formatting, tags and commit message guidelines applies to **mdadm**.

[Checkpatch](https://docs.kernel.org/dev-tools/checkpatch.html) script is run on
every patch in pull request so be sure that your commits are not generating
issues. There are some excludes, so the best is to follow github checkpatch action result.

Pull Request are closed by `Rebase and Merge` option, so it requires to keep every commit
meaningful. Kernel style requires that. The review changes must be pushed with **push --force**
to the chosen branch, then Pull Request will be automatically updated.

# Maintainers of mdadm repository on kernel.org

If there are differences between github and kernel.org, please contact kernel.org mdadm maintainers:

- Jes Sorensen <jes@trained-monkey.org>;
- Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>;

# Minimal supported kernel version

We do not support kernel versions below **v3.10**. Please be aware that maintainers may remove
workarounds and fixes for legacy issues.

# License

It is released under the terms of the **GNU General Public License version 2** as published
by the **Free Software Foundation**.