Posted to https://bugzilla.redhat.com/show_bug.cgi?id=1217185 I just stumbled on another bug while snapshotting and think it's related to 1210903 and 1197592 as it seems like some sort of race condition because it depends on what logging is in place and doesn't happen every time. Here are the details: I wrote this test script to snapshot and commit over and over: #!/bin/sh while [ 1 ]; do echo "Starting snapshot test `date`" virsh snapshot-create-as test 20150429 20150429-backup --disk-only --atomic virsh domblklist test virsh blockcommit test vda --active --pivot --verbose virsh snapshot-delete test 20150429 --metadata virsh domblklist test rm /glustervol1/vm/test/test.20150429 echo "Ending snapshot test `date`" echo echo sleep 2 done If I run libvirtd in the foreground with debug set to 1 I can't get it to fail, it does what it's supposed to do, snapshot and commit over and over. If I run libvirtd in the foreground with debug set to 3, then I will always eventually get this: Starting snapshot test Wed Apr 29 09:34:34 AKDT 2015 Domain snapshot 20150429 created Target Source ------------------------------------------------ vda /glustervol1/vm/test/test.20150429 hdc /dev/sr0 Block Commit: [100 %] Successfully pivoted Domain snapshot 20150429 deleted Target Source ------------------------------------------------ vda /glustervol1/vm/test/test.20150429 hdc /dev/sr0 Ending snapshot test Wed Apr 29 09:34:35 AKDT 2015 Starting snapshot test Wed Apr 29 09:34:37 AKDT 2015 error: unsupported configuration: source for disk 'vda' is not a regular file; refusing to generate external snapshot name Target Source ------------------------------------------------ vda /glustervol1/vm/test/test.20150429 hdc /dev/sr0 error: internal error: qemu block name '/glustervol1/vm/test/test.qcow2' doesn't match expected '/glustervol1/vm/test/test.20150429' error: Domain snapshot not found: no domain snapshot with matching name '20150429' Target Source ------------------------------------------------ vda /glustervol1/vm/test/test.20150429 hdc /dev/sr0 rm: can't remove '/glustervol1/vm/test/test.20150429': No such file or directory Ending snapshot test Wed Apr 29 09:34:37 AKDT 2015 At this point libvirt is confused about which file is the backing store because the first run did pivot after blockcommit, but didn't update the block file. From the logs: 2015-04-29 17:33:41.052+0000: 25192: warning : qemuDomainObjTaint:1972 : Domain id=2 name='test' uuid=4b9cc25b-68d1-4ce8-8a65-2a378e255e36 is tainted: high-privileges 2015-04-29 17:34:37.322+0000: 25191: error : virDomainSnapshotAlignDisks:609 : unsupported configuration: source for disk 'vda' is not a regular file; refusing to generate external snapshot name 2015-04-29 17:34:37.352+0000: 25194: error : qemuMonitorJSONDiskNameLookup:3977 : internal error: unable to find backing name for device drive-virtio-disk0 2015-04-29 17:34:37.354+0000: 25194: error : qemuMonitorJSONDiskNameLookupOne:3914 : internal error: qemu block name '/glustervol1/vm/test/test.qcow2' doesn't match expected '/glustervol1/vm/test/test.20150429' So libvirt insists that the block file is: root@wasvirt2:/glustervol1/vm/waspbx# virsh domblklist test Target Source ------------------------------------------------ vda /glustervol1/vm/test/test.20150429 hdc /dev/sr0 But that file isn't in use and isn't what qemu is using: root@wasvirt2:/glustervol1/vm/waspbx# lsof | grep test 25300 /usr/bin/qemu-system-x86_64 /var/log/libvirt/qemu/test.log 25300 /usr/bin/qemu-system-x86_64 /var/log/libvirt/qemu/test.log 25300 /usr/bin/qemu-system-x86_64 /glustervol1/vm/test/test.qcow2 The only way to straighten this out is to destroy and start the domain.