Manager of Linux Software RAID implemented through Multiple Devices driver.

Clone this repo:
  1. 4f3efc3 imsm: make freesize required to volume autolayout by Kinga Stefaniuk · 2 days ago main master
  2. 46f1927 imsm: fix first volume autolayout with IMSM_NO_PLATFORM by Mariusz Tkaczyk · 3 weeks ago
  3. 9dbd11e mdadm.h: provide basename if GLIBC is not avialable by Mariusz Tkaczyk · 3 weeks ago
  4. c5a4fe7 mdadm/tests: remove strace test by Xiao Ni · 2 weeks ago
  5. c36477f mdadm/tests: 05r1-re-add-nosuper by Xiao Ni · 2 weeks ago

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

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 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

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

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.


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