[Openstack] [nova] Disk attachment consistency

Richard W.M. Jones rich at annexia.org
Sun Aug 19 17:18:59 UTC 2012


On Mon, Aug 13, 2012 at 08:35:28PM -0700, Vishvananda Ishaya wrote:
> a) The device name only makes sense for linux. FreeBSD will select different device names, and windows doesn't even use device names. In addition xen uses /dev/xvda and kvm uses /dev/vda
> 
> b) The device sent in kvm will not match where it actually shows up. We can consistently guess where it will show up if the guest kernel is >= 3.2, otherwise we are likely to be wrong, and it may change on a reboot anyway

Another one -- possibly not a good one, but I'm including it for
completeness -- is that you preformat the disk with a partition and a
filesystem, then use the UUID or LABEL of the filesystem to mount
it[*], ie:

  mount UUID=abc-123-456 /data
  mount LABEL=os-data-disk /data

Naturally libguestfs can make these performatted disks (see the
'virt-format' tool, or do it through the API).
http://libguestfs.org/virt-format.1.html

Rich.

[*] I'm assuming here that Windows can find and mount filesystems
using the NTFS ID, but I don't know if that's true ...

-- 
Richard Jones
Red Hat




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