LVM Volume Group Quiesce/Resume

Abstract

The LVM volume group Quiesce/Resume feature available on HP-UX 11i v3 allows

quiescing reads/writes or just writes to the disks in a volume group to facilitate creating

a consistent snapshot of an otherwise active volume group for backup purposes.

This feature is designed to work in concert with backup management and disk array

management software in order to create a consistent snapshot of the disks that make up

an LVM volume group. The LVM Quiesce/Resume feature may also be used with a

hardware solution that can create a snapshot copy of all the disks. This feature assures

the data on the disks remains stable while the snapshot copy is made.

In the past, performing a disk backup of an LVM volume group typically involved un-

mounting and closing any open logical volumes and deactivating the volume group, to

keep the LVM metadata across all the disks consistent and unchanging. Now with the

introduction of the LVM Quiesce/Resume feature this is unnecessary. Application I/O

requests going through LVM, and LVM configuration and status metadata updates can

now be momentarily quiesced using new options to the vgchange command. This

allows taking a snapshot of all the disks in the volume group with the assurance that the

disk images will be consistent.