[Bug 251646] Re: {upstream} missing command to start *single* arrays in "auto-read" mode (like --incremental)

[ceg]

I don't think so.

My guess is that if initramfs calls

mdadm --incremental --run

it would run all arrays and not just the single array (mdX) that contains the root filesystem.
Degrading not yet fully available non-root arrays is bad, as it may nullify the redundancy and take hours to get the arrays resynced again.

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Title:
  {upstream} missing command to start *single* arrays in "auto-read"
  mode (like --incremental)

Status in mdadm - Tool for managing linux software RAID arrays.:
  New
Status in “mdadm” package in Ubuntu:
  Confirmed

Bug description:
  Binary package hint: mdadm

  Proposed command: "mdadm --incremental --run /dev/mdX"

  Initramfs must be able to start (selected) md devices in degraded mode
  (only the ones that contain the rootfs and swap/resume partition), if
  they didn't start after some time of udev hotplugging. Starting all
  arrays, that are not yet complete at that early stage, degraded is not
  acceptable.

  Initramfs could use the old non-incremental commands,

  ( i.e. "mdadm --run /dev/mdX" is preferable to "mdadm --assemble
  --scan" to start only selected array degraded)

  but the old commands break the support for "auto-read" mode set up and
  smooth inclusion of members that appear later on.

  
  Alternatively to a new --incremental option, make the old commands compatible and also start degraded arrays in "auto-read" mode and incrementally extendable by default.

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