Re: [libvirt-users] Attaching disks with external snapshots

Han, Did the same test again with libvirt debug enabled. This time I added the disk[1] without snaps (OK), and then added the disk[2] with snapshots. The libvirt log[3] (line 320) says: *Could not open '/opt/stack/data/nova/mnt/a3b4c6ddd9bf82edd4f726872be58d05/volume-a75b42e8-8175-4516-b724-43ee6f3d2520': Permission denied\r\n", "id": "libvirt-33"}]* But this file has 777 permissions. I can access it with any user I tried[4]. Tough its mounted over NFS, the permissions seems to be right. Erlon [1] http://paste.openstack.org/show/556055/ [2] http://paste.openstack.org/show/556056/ [3] http://pastebin.com/CCFcKq5b [4] http://paste.openstack.org/show/559018/ On Tue, Aug 16, 2016 at 2:41 PM, Erlon Cruz <sombrafam(a)gmail.com&gt; wrote: > Hi Han, > > Thanks for helping. What is the XML before the snapshot is created? Can > you post the XML files you used too? The files are in the links pointed by > the numbers [1], [2] etc. > > The versions are: > qemu-system-x86_64 --version > QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.4), Copyright > (c) 2003-2008 Fabrice Bellard > > libvirtd --version > libvirtd (libvirt) 1.3.1 > > > > Erlon > > On Mon, Aug 15, 2016 at 12:56 AM, Han Han <hhan(a)redhat.com&gt; wrote: > >> Hi，Erlon >> I was not able to reproduce your problem. It is ok to attach disk with >> external snapshot. >> I did it with following steps: >> # qemu-img create /tmp/vdb 100M >> Formatting '/tmp/vdb', fmt=raw size=104857600 >> # virsh start snap >> Domain snap started >> # virsh snapshot-create-as snap s1 --disk-only --diskspec >> vdb,file=/tmp/vdb.s1 --quiesce >> Domain snapshot s1 created >> # virsh dumpxml snap|awk '/<disk/,/<\/disk/' >> <disk type='file' device='disk'> >> <driver name='qemu' type='qcow2' cache='none'/> >> <source file='/var/lib/libvirt/images/snap.s1'/> >> <backingStore type='file' index='1'> >> <format type='qcow2'/> >> <source file='/var/lib/libvirt/images/snap.qcow2'/> >> <backingStore/> >> </backingStore> >> <target dev='vda' bus='virtio'/> >> <alias name='virtio-disk0'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x07' >> function='0x0'/> >> </disk> >> <disk type='file' device='disk'> >> <driver name='qemu' type='qcow2'/> >> <source file='/tmp/vdb.s1'/> >> <backingStore type='file' index='1'> >> <format type='raw'/> >> <source file='/tmp/vdb'/> >> <backingStore/> >> </backingStore> >> <target dev='vdb' bus='virtio'/> >> <alias name='virtio-disk1'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' >> function='0x0'/> >> </disk> >> >> Save the dumped vdb's xml to /tmp/vdb.xml >> # virsh detach-device snap /tmp/vdb.xml >> Device detached successfully >> # virsh attach-device snap /tmp/vdb.xml >> Device attached successfully >> # virsh dumpxml snap|awk '/<disk/,/<\/disk/' >> <disk type='file' device='disk'> >> <driver name='qemu' type='qcow2' cache='none'/> >> <source file='/var/lib/libvirt/images/snap.s1'/> >> <backingStore type='file' index='1'> >> <format type='qcow2'/> >> <source file='/var/lib/libvirt/images/snap.qcow2'/> >> <backingStore/> >> </backingStore> >> <target dev='vda' bus='virtio'/> >> <alias name='virtio-disk0'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x07' >> function='0x0'/> >> </disk> >> <disk type='file' device='disk'> >> <driver name='qemu' type='qcow2'/> >> <source file='/tmp/vdb.s1'/> >> <backingStore type='file' index='1'> >> <format type='raw'/> >> <source file='/tmp/vdb'/> >> <backingStore/> >> </backingStore> >> <target dev='vdb' bus='virtio'/> >> <alias name='virtio-disk1'/> >> <address type='pci' domain='0x0000' bus='0x00' slot='0x0c' >> function='0x0'/> >> </disk> >> >> So I managed to attach disks with snapshot. >> I want to know what is your libvirt and qemu-kvm version? >> And can you provide your files: /tmp/disk.xml[1], >> /tmp/snap-from-disk.xml[2], /tmp/disk-with-snap.xml[4], >> /tmp/disk-with-snap.xml . I need more details. >> >> Han Han >> >> ----- Original Message ----- >> From: "Erlon Cruz" <sombrafam(a)gmail.com&gt; >> To: libvirt-users(a)redhat.com >> Sent: Friday, August 12, 2016 10:23:24 AM >> Subject: [libvirt-users] Attaching disks with external snapshots >> >> Hi folks, >> >> I'm trying to to attach a disk to an instance using libvirt. The problem >> is, this disk has external snapshots. The process tried was: >> >> 1 - Attach a disk in the domain: >> virsh# attach-device instance-00000006 /tmp/disk.xml[1] --live >> >> 2 - Snapshot the disk[2]: >> virsh# snapshot-create instance-00000006 --quiesce --xmlfile >> /tmp/snap-from-disk.xml[2] --disk-only >> >> 3 - Dump the domain XML and create a new disk file from it: >> virsh# dumpxml instance-00000006 >> ... [3] >> >> 4 - Dettach the device and re-add it using the new disk file: >> virsh# detach-device instance-00000006 /tmp/disk-with-snap.xml[4] >> Device detached successfully >> virsh# attach-device instance-00000006 /tmp/disk-with-snap.xml >> error: Failed to attach device from /tmp/disk-with-snap.xml >> error: internal error: unable to execute QEMU command 'device_add': >> Property 'virtio-blk-device.drive' can't find value 'drive-virtio-disk1' >> >> Question, is this operation supported? If yes, how is the correct >> procedure? >> >> Erlon >> >> >> [1] http://paste.openstack.org/show/556055/ >> [2] http://paste.openstack.org/show/556056/ >> [3] http://paste.openstack.org/show/556063/ >> [4] http://paste.openstack.org/show/556064/ >> >> _______________________________________________ >> libvirt-users mailing list >> libvirt-users(a)redhat.com >> https://www.redhat.com/mailman/listinfo/libvirt-users >> > >