[libvirt] LVM storage pool with existing mirrored volumes

Hi, I tried to setup a lvm-backed storage pool, reusing an existing volume group which already contains a handful of mirrored logical volumes. For reference, I am using lvm 2.02.56-r3, qemu-kvm 0.12.1.2 and libvirt 0.7.5 on an up-to-date ~amd64 gentoo system. The first issue I encountered is when trying to activate the storage pool, the process fails with "internal error lvs command failed". This appears to be because the output of lvs is slightly different when using mirrored lvs, and is breaking the parser: /sbin/lvs --separator , --noheadings --units b --unbuffered --nosuffix --options lv_name,origin,uuid,devices,seg_size,vg_extent_size bigpool vms,,0PzrRS-8Ljs-SUq0-ywFH-BI3d-RI0V-aibupu,vms_mimage_0(0),vms_mimage_1(0),107374182400,4194304 backups,,Snk2NL-oJe3-GpTL-Qihs-ZjjG-xPyj-ufmwCp,backups_mimage_0(0),backups_mimage_1(0),214748364800,4194304 The device column of output would normally contain something like "/dev/sda(1234)", but here contains "vms_mimage_0(0),vms_mimage_1(0). This is causing the parser to misinterpret the output, and it believes the lv name to be suffixed with a trailing comma, eg "vms,". When trying to access "/dev/bigpool/vms,", the command errors with File or Directory not Found. When adding the --all parameter to lvs, the hidden mirroring lvs are visible, and these have the expected structure: vms,,0PzrRS-8Ljs-SUq0-ywFH-BI3d-RI0V-aibupu,vms_mimage_0(0),vms_mimage_1(0),107374182400,4194304 [vms_mlog],,vnOzg8-ynKc-kM8F-RKdM-xXC0-PJlG-qcgmFh,/dev/sda2(0),4194304,4194304 [vms_mimage_0],,2pXjHt-aARa-FOO7-ZL6N-ahpu-ebdr-P6Qxj3,/dev/sdb1(0),107374182400,4194304 [vms_mimage_1],,ITd8CT-JpKi-Y2a6-a4jc-2yDa-9VmG-gWgRd8,/dev/sdc1(51200),107374182400,4194304 Presumably, without the --all parameter and listing the internal mirroring volumes, libvirt will miscalculate sizes of LVs in the VG. This bug appears to prevent the use of any volume group which contains one or more mirrored logical volumes as a backend storage pool. -- Ben Roberts Computer Science MEng, Part IV Electronics and Computer Science, University of Southampton