So, on discovering a server that’s configured with the wrong disk layout, I find myself needing to consolidate all logical volumes onto a single physical volume (PV) so I can re-configure the other PV. The machine has the disk space, so it should be a matter of shuffling bits in a “shell-game” so I can clear off the second PV and re-build the disk array with the right RAID level.<\/p>\n
LVM2 has the utility pvmove that can move physical extents from one disk to another. Maybe I can make this work for me \ud83d\ude42<\/p>\n
First hurdle: all physical disk blocks are allocated to LVM physical volumes. I need to shrink my first PV to make room for blocks from my second PV. To see how many blocks on PV 1 are in use, I run<\/p>\n
pvdisplay -m<\/pre>\nWhich reports that all extents up to 96640 are in use. So I should be able to shrink the PV down to, say, 100000 extents safely. With 32MiB extents, the command to do this should be<\/p>\n
pvresize -t \/dev\/sda3 --setphysicalvolumesize 3200000M<\/pre>\nbut I’m too chicken to run this on a live system. I need to set up a test machine to verify that this works.<\/p>\n
UPDATE: So, it does work, but it turns out that a reboot is needed to update the kernel partition table after the next step, which is resizing the partitions.<\/p>\n
(It might have been easier to just resize the partition first and then resize the PV with “pvresize \/dev\/sda3” and let it fill the new partition.)<\/p>\n
After shrinking the sdb1 partition to match the new PV size, create a new partition, sda4, to hold the new PV. Create the new PV (I did it in system-config-lvm) and add it to the volume group (VG) of the logical volumes we want to move off of sdb1 as extents must be moved to a new PV in the same group.<\/p>\n
I’m testing this on a VM now. I’ve already determined this will require a reboot, so I’m less enthused about the process already. :-\/<\/p>\n","protected":false},"excerpt":{"rendered":"
So, on discovering a server that’s configured with the wrong disk layout, I find myself needing to consolidate all logical volumes onto a single physical volume (PV) so I can re-configure the other PV. The machine has the disk space, … Continue reading