On Tue, Nov 04, 2008 at 06:32:37PM +0100, Chris Lalancette wrote: > Assume that you have an iSCSI target available, and on that iSCSI target 1 LUN > is exported. On that 1 LUN, you have an LVM volume group (say, myvg), with 2 > logical volumes (say, lv1 and lv2). Now you execute the following sequence of > commands: > > 1) virsh define iscsi_pool.xml > 2) virsh start iscsi_pool > 3) virsh find-storage-pool-sources-as logical > > With that sequence, you would expect step 3) to return XML similar to: > > <sources><source><name>myvg</name><device path='/dev/sdb'/></source></sources> > > However, what you instead get is: <sources/>. That's because if you just try to > do storage pool discovery on a logical pool without ever touching the logical > pool in any fashion, pvs (what we use to do discovery) doesn't return anything. > If you touch the logical volume group at all (say, with vgscan), they then > suddenly appear. To make sure we see all of the potential volume groups when > doing pool discovery, make sure to run vgscan before we run pvs. With this > patch in place, logical discovery just does the right thing. ACK, this makes total sense.