![\"\"](\"https:\/\/www.hutsky.cz\/blog\/wp-content\/uploads\/4-virtual-machines-300px.png\")
I installed Centos 7 on a brand new machine about a half a year ago, and set up KVM with two data pools – one just a regular directory for old raw images, the second being an LVM volume group. Later, I added one additional physical disk to the machine, for local backups, which turned out to be an important detail later.<\/p>\n
Nowadays I wanted to start a new virtual machine but to my surprise, the data pool based on LVM volume group ‘vg2’ wasn’t active:<\/p>\n
# virsh pool-list\r\nName State Autostart \r\n-------------------------------------------\r\nbackups active yes \r\nvg2 inactive yes<\/pre>\nThe LVM itself seemed to be working just fine, as well as the one virtual machine which was already residing in a logical volume in this particular data pool. But the data pool would not get activated, no matter if I tried from virsh:<\/p>\n
unsupported configuration: cannot find any matching source devices for logical volume group 'vg2'<\/pre>\nor from virt-manager:<\/p>\n
Error starting pool 'vg2': unsupported configuration: cannot find any\r\nmatching source devices for logical volume group 'vg2'<\/pre>\nEventually, it turned out that when I had added the physical disk for backups into the machine back then, this new disk got \/dev\/sda<\/strong> assigned while the original old disk got \/dev\/sdb<\/strong> as the device name. LVM was able to cope with the change, but libvirt remembered the original value:<\/p>\n
# virsh pool-dumpxml vg2\r\n<pool type='logical'>\r\n <name>vg2<\/name>\r\n <uuid><\/uuid>\r\n <capacity unit='bytes'>1351803207680<\/capacity>\r\n <allocation unit='bytes'>461373440000<\/allocation>\r\n <available unit='bytes'>890429767680<\/available>\r\n <source>\r\n <device path='\/dev\/sda7'\/>\r\n <name>vg2<\/name>\r\n <format type='lvm2'\/>\r\n <\/source>\r\n <target>\r\n <path>\/dev\/vg2<\/path>\r\n <\/target>\r\n<\/pool><\/pre>\n