[Bug 1615650] Re: Guided Partitioning does not list Software RAID devices on NVMe

[Mauricio Faria de Oliveira]

@taco-screen-team, may @cyphermox check this one? we've worked on this
area/kind of bugs in the past.

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Title:
  Guided Partitioning does not list Software RAID devices on NVMe

Status in partman-auto package in Ubuntu:
  New

Bug description:
  == Comment: #0 - Mauricio Faria De Oliveira <mauricfo at br.ibm.com> - 2016-08-19 14:56:18 ==
  ---Problem Description---
  Guided Partitioning does not list Software RAID devices on NVMe

  This happens because commit [1] in partman-auto only lists mdadm arrays in wholedisk devices.
  It filters out any array whose slave devices have a trailing 'p<number>', and that is used by NVMe (e.g., nvme0n1p2).

  There should be an exception for NVMe devices, since the installer requires that mdadm arrays are created in partitions
  (the 'Configure Software RAID' process automatically creates partitions even if you select wholedisk devices).
  Another option is for that restriction to be removed (it seems conflicting/confusing w/ this installer behavior nowadays).

  The attached patch adds an exception for NVMe, the conservative
  approach, since this is wanted in 16.04 LTS. (patch also applies on
  16.10 -- identical partman-auto versions).

  [1] https://anonscm.debian.org/cgit/d-i/partman-auto.git/commit/lib
  /auto-shared.sh?id=7dfd6208c3f8e4cf574cab22c81241a80aba6cfb

  
  Function path:
  ---

  @ /lib/partman/lib/auto-shared.sh
  1. select_auto_disk() 
  2. get_auto_disks()
  3. is_wholedisk_mdraid()

  
  Demonstration:
  ---

  Software RAID device:

  ~ # grep ^md /proc/mdstat
  md0 : active raid1 nvme1n1p1[1] nvme0n1p1[0]

  ~ # ls -1 /sys/block/md0/slaves
  nvme0n1p1
  nvme1n1p1

  
  1) Notice there's no 'RAID1 device #0' in this list:

  
    ?????????????????????????? [!!] Partition disks
    ?
    ? Note that all data on the disk you select will be erased, but not
    ? before you have confirmed that you really want to make the changes.
    ?
    ? Select disk to partition:
    ?
    ?          /dev/nvme0n1 - 1.6 TB Unknown
    ?          /dev/nvme1n1 - 1.6 TB Unknown
    ?          SCSI1 (0,0,0) (sda) - 137.4 GB QEMU QEMU HARDDISK
    ?
    ?     <Go Back>

  2) Make this change (Go Back to main menu, then Execute a Shell)
  ~ # sed -i '243 i */nvme*) ;;' /lib/partman/lib/auto-shared.sh

  3) Now the array is listed:

    ?????????????????????????? [!!] Partition disks 
    ?
    ? Note that all data on the disk you select will be erased, but not
    ? before you have confirmed that you really want to make the changes.
    ?
    ? Select disk to partition:
    ?
    ?          RAID1 device #0 - 1.6 TB Software RAID device
    ?          /dev/nvme0n1 - 1.6 TB Unknown
    ?          /dev/nvme1n1 - 1.6 TB Unknown
    ?          SCSI1 (0,0,0) (sda) - 137.4 GB QEMU QEMU HARDDISK
    ?
    ?     <Go Back>


  
   
  Contact Information = Mauricio Faria de Oliveira <mauricfo at br.ibm.com 
   
  ---uname output---
  Linux ubuntu 4.4.0-31-generic #50-Ubuntu SMP Wed Jul 13 00:05:18 UTC 2016 ppc64le GNU/Linux
   
  Machine Type = N/A 
   
  ---boot type---
  CDROM / ISO image
   
  ---Install repository type---
  CDROM
   
  ---Point of failure---
  Other failure during installation (stage 1)

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