[Bug 1683105] Re: Installation of DMRaid should automatically add necessary modules to /etc/initramfs-tools/modules

[David Lee]

Well, tbh, I am having similar issues on another machine running RAID-0
(striped), so I do think that dm-raid is required on that too. Maybe
it's RAID-1 (mirror) that doesn't need it but instead needs the dm-
mirror module?

In any case, I understand the risks. I'm trying this out as research
because there are circumstances that using "fakeraid" may be beneficial,
for example recent cases where several Lenovo and Asus laptops are
locked into "fakeraid" in addition to Secure Boot as a form of lock in
to Windows 10- I'm convinced that with the use of kpartx + dmraid and
proper disk preparation, one could get those working with Linux without
the use of kernel hacks (my machines currently have their disks set up
as GPT, but with a MBR compatibility partition for booting legacy GRUB).

I'm also interested in the aspect where the system would assign memory
for read-caching to further improve performance (one AMD system I have
assigns 256MB of system memory for this).

I also wish to research NVidia's claim that the NForce's RAID is
hardware accelerated (both machines I have the RAID issue on runs off
these NForce 980a motherboards).

Lastly, I use drive trays on one of the two builds, it seems to have
reliability issues if the drives in them are set up as AHCI, but behaves
properly if the drives are set up as RAID-0.

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https://bugs.launchpad.net/bugs/1683105

Title:
  Installation of DMRaid should automatically add necessary modules to
  /etc/initramfs-tools/modules

Status in dmraid package in Ubuntu:
  Triaged

Bug description:
  This is related to bug 1313169, I have had a sudden bout of clarity on
  the cause of the issue.

  I propose this modification to the dmraid installation script as it is
  a small but necessary enhancement.

  When dmraid is installed, it adds all the necessary hooks to
  initramfs-tools. However, it has one oversight, that the required raid
  modules are not added to /etc/initramfs-tools/modules. Without these
  modules, dmraid will inevitably fail to initialize the array when
  started since the kernel would not be able to find the required
  modules in the image.

  I propose that when dmraid is installed, during installation the
  script would check to see if the following items are already in /etc
  /initramfs-tools/modules, and append the required modules into the
  bottom of the file if it's not, and then rebuild the initramfs, update
  grub and if necessary reinstall grub. On uninstall of package, I
  propose that we should just warn the user but leave the lines in just
  in case they're using something else that also needs the modules.

  The following modules should be appended to the /etc/inmitramfs-
  tools/modules file:

  raid0
  dm_raid
  raid1
  raid10
  raid456
  async_raid6_recov
  async_memcpy
  async_pq
  async_tx
  raid6_pq
  async_xor
  xor
  libcrc32c

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