[Bug 531240] Re: breaking raid: root raid_member opened as luks

[ceg]

** Also affects: ubuntu-release-notes
   Importance: Undecided
       Status: New

** Description changed:

  Binary package hint: util-linux
+ 
+ When using luks on top of software raid devices, linux_raid_member
+ devices can get opened as luks instead of being assembled into md
+ devices.
+ 
+ ----
  
  After the member is opened as luks device it is booted instead of the md
  device, while the raid remains "inactive".
  
  I first noticed /proc/mdstat reported the root raid as inactive
  (although the system seemed to run fine!).
  
  Looking further it seemed like during boot the system has unlocked and mounted the rootfs using (only) one raid_member located on an external usb disk directly. ("dmsetup deps" pointed to it for mdX_crypt)
  I guess since the usb raid_member was busy then, the system was not able to start the raid, and so it remained inactive.
  
  Which part of the system is involved in setting up the root and could
  have messed things up here?
  
  Calling "sudo blkid" reported what actually is an USB
  "linux_raid_member" as TYPE="crypto_LUKS".
  
  @util-linux
  I found the following in the util-linux changelog:
    * Always return encrypted block devices as the first detected encryption
       system (ie. LUKS, since that's the only one) rather than probing for
       additional metadata and returning an ambivalent result.  LP: #428435.
  might that cause the precedence of reporing luks over raid_member for the usb disk?
  
  @cryptsetup
  Also "cryptsetup isLuks" gives a false positve. "cryptsetup isLuks <raid member device with luks on it>" returns $?=0 (success/true) That is the reason why the initramfs check implemented in scripts/local-top/cryptroot does not prevent this bug from having its bad effects.
  
  Edit: Happens according to the order of device enumeration on boot
  (random assembly). Another symptom is the alternate CD's rescue-mode
  wants to open internal raid members just as well, so it's not usb
  dependent.

** Description changed:

  Binary package hint: util-linux
  
  When using luks on top of software raid devices, linux_raid_member
  devices can get opened as luks instead of being assembled into md
- devices.
+ devices. It is adviseable not to use luks on raid.
  
  ----
  
  After the member is opened as luks device it is booted instead of the md
  device, while the raid remains "inactive".
  
  I first noticed /proc/mdstat reported the root raid as inactive
  (although the system seemed to run fine!).
  
  Looking further it seemed like during boot the system has unlocked and mounted the rootfs using (only) one raid_member located on an external usb disk directly. ("dmsetup deps" pointed to it for mdX_crypt)
  I guess since the usb raid_member was busy then, the system was not able to start the raid, and so it remained inactive.
  
  Which part of the system is involved in setting up the root and could
  have messed things up here?
  
  Calling "sudo blkid" reported what actually is an USB
  "linux_raid_member" as TYPE="crypto_LUKS".
  
  @util-linux
  I found the following in the util-linux changelog:
    * Always return encrypted block devices as the first detected encryption
       system (ie. LUKS, since that's the only one) rather than probing for
       additional metadata and returning an ambivalent result.  LP: #428435.
  might that cause the precedence of reporing luks over raid_member for the usb disk?
  
  @cryptsetup
  Also "cryptsetup isLuks" gives a false positve. "cryptsetup isLuks <raid member device with luks on it>" returns $?=0 (success/true) That is the reason why the initramfs check implemented in scripts/local-top/cryptroot does not prevent this bug from having its bad effects.
  
  Edit: Happens according to the order of device enumeration on boot
  (random assembly). Another symptom is the alternate CD's rescue-mode
  wants to open internal raid members just as well, so it's not usb
  dependent.

-- 
breaking raid: root raid_member opened as luks
https://bugs.launchpad.net/bugs/531240
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