F38 proposal: Use mdadm for BIOS RAID Support in Anaconda (Self-Contained Change proposal)

[Ben Cotton]

https://fedoraproject.org/wiki/Changes/UseMdadmForBIOSRAIDInAnaconda

This document represents a proposed Change. As part of the Changes
process, proposals are publicly announced in order to receive
community feedback. This proposal will only be implemented if approved
by the Fedora Engineering Steering Committee.


== Summary ==
Use mdadm instead of dmraid to support BIOS RAID (Firmware RAID or
Fake RAID) during the Fedora installation process.

== Owner ==
* Name: [[User:vtrefny| Vojtech Trefny]] (Blivet)
* Email: vtrefny AT redhat.com
* Name: [[User:vponcova|Vendula Poncova]] (Anaconda)
* Email: vponcova AT redhat.com


== Detailed Description ==
[[Anaconda]] (or to be more precise [[Blivet]], the storage library
Anaconda uses) is currently using dmraid to support the BIOS RAID
devices (sometimes also called Firmware or BIOS RAID) during
installation. We plan to replace dmraid by mdadm, which we are
currently using for software RAID management. The main reason is that
dmraid is no longer actively maintained. mdadm supports the two major
BIOS RAID technologies: Common RAID Disk Data Format (DDF)
[https://www.snia.org/tech_activities/standards/curr_standards/ddf
standard by SNIA] and
[https://www.intel.com/content/www/us/en/support/products/122484/memory-an...
Intel Matrix Storage Manager] format. mdadm is missing support for
some older BIOS RAID formats that existed before DDF and are still
supported by dmraid so by implementing this change, we will remove
support for some BIOS RAID formats from the installer.

== Feedback ==

We tried to
[https://lists.fedoraproject.org/archives/list/[e-mail].o...
get feedback from the community] to find out how many users use BIOS
RAID and would be affected by this change (especially by removing
support for the older formats). The only response was from the Fedora
QA which has an Intel Matrix machine for testing which should be
supported by mdadm.

== Benefit to Fedora ==

Replacing a tool/library that is no longer being actively developed
and maintained. Because we are replacing it with a tool that is
currently used for software RAID management in the installer, this
also means removing one dependency from the installer environment and
remove the dmraid startup service from the installed system.

== Scope ==
* Proposal owners: Changes to Blivet (replacing dmraid with mdadm for
the specified BIOS RAID formats) and Anaconda (removing the
`inst.nodmraid` flag)

* Other developers:

* Release engineering:
* Policies and guidelines: N/A (not needed for this Change)
* Trademark approval: N/A (not needed for this Change)
* Alignment with Objectives:


== Upgrade/compatibility impact ==

This change will affect only new installations (the change only
changes behaviour of the installer).


== How To Test ==
A hardware with BIOS RAID support (DDF or IMSM) is required. (Creating
a "fake" BIOS RAID with mdadm might be possible for testing, we'll add
steps for testing without the hardware later (if possible).)

Follow the test case for installing on BIOS/Firmware RAID:
[[QA:Testcase_install_to_firmware_RAID]].


== User Experience ==
Users with supported BIOS RAIDs shouldn't notice a change, the
installation should work the same for them. Users with older
unsupported BIOS RAID formats won't be able to install Fedora on these
arrays. For these users we'll recommend switching to software RAID.

== Dependencies ==


== Contingency Plan ==
* Contingency mechanism: Revert the changes and keep using dmraid for
all BIOS RAID formats.
* Contingency deadline: Beta  <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
* Blocks release? No


== Documentation ==
N/A (not a System Wide Change)

== Release Notes ==


-- 
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis