Here's a way to do some tests (assuming libguestfs from git which has
the mdadm package):
$ rm /tmp/test1.img /tmp/test2.img
$ truncate -s 1G /tmp/test1.img /tmp/test2.img
$ ./run ./rescue/virt-rescue -a /tmp/test1.img -a /tmp/test2.img
[At this point you have to switch to another terminal and kill the
rogue 'sed' and/or 'grep' processes launched by libtool --
https://bugzilla.redhat.com/show_bug.cgi?id=729052]
<rescue> mdadm --create /dev/md0 -l1 -n2 /dev/vda /dev/vdb
<rescue> blockdev --getsize64 /dev/md0
1073729536
<rescue> cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 vdb[1] vda[0]
1048564 blocks super 1.2 [2/2] [UU]
unused devices: <none>
<rescue> mkfs -t ext3 /dev/md0
<rescue> mount /dev/md0 /sysroot
<rescue> touch /sysroot/hello-world
<rescue> exit
Oddly this allocates all the space on the second disk, but not the
first:
$ du -sh /tmp/test1.img /tmp/test2.img
33M /tmp/test1.img
1.0G /tmp/test2.img
Then try it in guestfish (add the -v option for more detail):
$ ./run ./fish/guestfish -a /tmp/test1.img -a /tmp/test2.img
<fs> run
<fs> vfs-type /dev/vda
linux_raid_member
Like you, I don't see any /dev/md0 device (but also I don't see any
weird names either). Does md need a daemon of some sort?
Rich.
--
Richard Jones, Virtualization Group, Red Hat
http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine. Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/