Q. I am trying to reduce the time needed to mirror a series of lvols by running all of them simultaneously. This seems to work on all volume groups except vg00. They are mirrored but the mirror will not boot.
A. The problem is that each extent is allocated from the available PVs in the order received. If all the lvextend commands are run at one time, there is no guarantee that the first lvol will get the first extents – a requirement for a bootable mirror. A quick check using lvdisplay –v will show that the first extent on the mirror is not zero. And some casual testing shows that a parallel versus serial lvextend on vg00 runs about the same time. This result can be inferred by the nature of the mirroring process: To ensure that each extent is accurately copied, the LVM subsystem locks the extent to prevent changes, copies the extent to the mirror, then verifies the copy. This task highly serializes all the tasks, thus no improvement with parallel syncing.
– See more at: http://serviceitdirect.com/blog/parallel-mirroring-vg00-boot-problems#sthash.WgCVKBLf.dpuf
Tags: HP-UX