84 lines
3.5 KiB
Markdown
84 lines
3.5 KiB
Markdown
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**mdadm** is a utility used to create and manage **software RAID** devices implemented through
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**Multiple devices driver (MD)** in kernel. It supports following RAID metadata formats:
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* [Linux native RAID](https://raid.wiki.kernel.org/index.php/RAID_superblock_formats):
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Known as **native** or **native RAID**. First and default metadata format. Metadata management
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is implemented in **MD driver**.
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* Matrix Storage Manager Support (no reference, metadata format documentation is proprietary).
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Known as **IMSM**. Metadata format developed and maintained by **Intel®** as a part of **VROC**
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solution. There are some functional differences between **native** and **imsm**. The most
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important difference is that the metadata is managed from userspace.
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**CAUTION:** **imsm** is compatible with **Intel RST**, however it is not officially supported.
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You are using it on your own risk.
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* [Common RAID DDF Specification Revision](https://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf)
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**IMPORTANT:** DDF is in **maintenance only** mode. There is no active development around it.
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Please do not use it in new solutions.
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# How to Contribute
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**mdadm** is hosted on [kernel.org](https://kernel.org/). You can access repository
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[here](https://git.kernel.org/pub/scm/utils/mdadm/mdadm.git).
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It is maintained similarly to kernel, using *mailing list*. Patches must be send through email.
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Please familiarize with general kernel
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[submitting patches](https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html)
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documentation. Formatting, tags and commit message guidelines applies to **mdadm**.
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## Sending patches step-by-step
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To maximize change of patches being taken, follow this instruction when submitting:
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1. Create possibly logically separated commits and generate patches:
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Use ``git format-patch --cover-letter --signoff -v <nr>`` to create patches:
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* ``--cover-letter`` can be skipped if it is only one patch;
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* ``--signoff`` adds sign-off tag;
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* ``-v <nr>`` indicates review revision number, sender should increment it before resending.
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2. Check style of every patch with kernel
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[checkpatch](https://docs.kernel.org/dev-tools/checkpatch.html) script:
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It is important to keep same coding style that is why in **mdadm**
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[kernel coding style](https://www.kernel.org/doc/html/v4.10/process/coding-style.html)
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is preferred. ``checkpath --no-tree <patch_file>`` can be used to verify patches.
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Following checkpatch issues can be ignored:
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- New typedefs.
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- comparing with *True/False*.
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- kernel *MAINTAINERS* file warning.
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- *extern* keyword in headers.
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3. Send patches using ``git send-mail --to=linux-raid@vger.kernel.org <cover-letter> <patch1> <patch2> (...)``
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# Maintainers
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It is good practice to add **mdadm maintainers** to recipients for patches:
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- Jes Sorensen <jes@trained-monkey.org>;
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- Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>;
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Adding **MD maintainers** could be reasonable, especially if patches may affect MD driver:
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- Song Liu <song@kernel.org>;
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- Yu Kuai <yukuai3@huawei.com>;
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# Reviewers
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**mdadm** utility is not part of kernel tree, so there is no certificated *Reviewers* list. Everyone
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can comment on mailing list, last decision (and merging) belongs to maintainers.
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# Minimal supported kernel version
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We do not support kernel versions below **v3.10**. Please be aware that maintainers may remove
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workarounds and fixes for legacy issues.
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# License
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It is released under the terms of the **GNU General Public License version 2** as published
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by the **Free Software Foundation**.
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