Quiesce and read-only VG

[WW451512]

Hi All,

Just wanted to know what is the main difference between a Quiesce mode and read-only mode for VGs (for 11iv3).
As per docs quiesce mode is used for taking snapshots/backups, but can we take backup of VGs in read-only mode also?

Thanks

[Torsten.]

You can quiesce a VG during taking a snapshot to ensure your data is consistent, e.g. disallow write operations for 10min:

# vgchange -Q w -t 600 vg08


If you set a VG into ro mode, you should be able to read for backup - why not?

But normally you create a snapshot or something similar, then backup from there.

[likid0]

the difference is in operation, let's say you want to take a backup of a FS mounting a VG read-only. You need to:

- stop app
- unmount FS
- deactivate vg
- activate vg in rw
- mount fs
- take backup


with Quiesce:

- stop app(if you need to)
- quiesce the vg
- take backup