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[Xen-users] Setting up XEN domU causes RAID5 to fail?

  • To: <xen-users@xxxxxxxxxxxxx>
  • From: "Marc Tousignant" <myrdhn@xxxxxxxxx>
  • Date: Sun, 16 Sep 2012 13:28:06 -0400
  • Delivery-date: Sun, 16 Sep 2012 17:29:23 +0000
  • List-id: Xen user discussion <xen-users.lists.xen.org>
  • Thread-index: Ac2ULEQ+iZ4G3QhYQkWQx6+MidWqNQ==

This may be a coincidence or not, but I’m building a new XEN system for myself for work purposes.

I support several different versions of a software that cannot be installed at the same time, so I decided I wanted to setup a XEN domU for each.


I had 5 spare 500GB drives so I put them in my system and partitioned them so I have a RAID1 boot, a RAID5 root and a RAID5 images.

I got linux (Funtoo) installed on the root with my kernel on the boot. XEN is installed as well and setup and running.

I created a xen_images folder and a iso _images folder both in the /images folder.

I downloaded the ISO’s for the OS’s I need to install into iso_images.

I then created several .img files in the xen_images folder using dd. For example (dd if=/dev/zero of=/images/xen_images/Win7x86_Base.img bs=1 count=1 seek=50G)


I then started my first xen domU booting from the Win7 ISO I had and started the install.

I got to the point where it formatted the “drive” and started installing, it failed on the extraction step saying my “DVD” was bad.

When I went back to check the md5/sha on the ISO I noticed that both of my RAID5’s “lost” several members. The RAID1 is fine.

Strangely enough the system stays up with an OS drive that is supposedly failed, granted a lot of functionality is lost, like missing files etc on the missing parts of the RAID5 root


# cat /proc/mdstat

Personalities : [raid1] [raid6] [raid5] [raid4] [multipath]

md2 : active raid5 sda5[0](F) sde5[4](F) sdd5[3](F) sdc5[2] sdb5[1]

      1724864512 blocks super 1.2 level 5, 512k chunk, algorithm 2 [5/2] [_UU__]


md1 : active raid5 sda4[5](F) sde4[6](F) sdd4[7](F) sdc4[2] sdb4[1]

      209713152 blocks level 5, 512k chunk, algorithm 2 [5/2] [_UU__]


md0 : active raid1 sda1[0] sde1[4] sdd1[3] sdc1[2] sdb1[1]

      511936 blocks [5/5] [UUUUU]


If I check the drives I get informed that the md superblock has vanished on the missing drives.

A reboot fails, because the RAID5’s are out of sync, and I have to go into the busybox shell in order to repair them.

After repairing, and forcing a fsck, the system checks out again as good. I cannot get it to fail the RAID5’s again unless I attempt to start the domU install again.


Anyone run into this or something similar before?



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