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:

  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

  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.

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 first.

How to Contribute

Effective immediately Github is the primary location for mdadm. Use pull request to contribute.

It was originally hosted on kernel.org. You can access the old repository here.

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 documentation. Formatting, tags and commit message guidelines applies to mdadm.

Checkpatch 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.