Re: [Qemu-devel] virtio_blk unique device ID

[Ryan Harper <ryanh@us.ibm.com>]

* Jule Slootbeek <jsslists@gmail.com> [2009-01-29 16:13]:
> All,
> I was recently testing the workings of virtio to provision SAN block devices
> to a domain, which worked great! However, i could not find a way to find the
> UID of a virto_blk device. The scenario I had created was the following. a
> LUN provisioned to my KVM (kvm-83) hypervisor over two paths, both paths
> mapped to my domain using virtio_blk. When configuring multipath-tools in
> the domain I could not find a way to find the UID of the LUN in order to
> create the multipath config. On a SCSI device, I would use the
> /lib/udev/scsi_id tools to discover this ID. I am using libvir/qemu 0.5.1 in
> Ubuntu Jaunty Alpha-3 as hypervisor and virtual machine.
> Does the virtio_blk driver provide a UID to its devices, and is there a way
> to get this ID in userspace?

use uuid?  Some distros (Ubuntu for example) mount via UUID

% blkid 
/dev/vda1: UUID="6331275f-f10d-4684-8aa8-e8aca1582b9d" TYPE="swap" 
/dev/vda2: UUID="cf121062-fd27-4151-8a68-6cb940e449fe" TYPE="ext3" 

# ls -al /dev/disk/by-uuid/
total 0
lrwxrwxrwx 1 root root 10 Jan 29 17:10 6331275f-f10d-4684-8aa8-e8aca1582b9d -> ../../vda1
lrwxrwxrwx 1 root root 10 Jan 29 17:10 cf121062-fd27-4151-8a68-6cb940e449fe -> ../../vda2

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
ryanh@us.ibm.com