topic Re: Another HP-UX Mirroring Question in Operating System - HP-UX

Another HP-UX Mirroring Question

Stevereno_1 — Sat, 22 May 2010 19:07:25 GMT

Greetings,
I believe I have successfully implemented mirroring on an older HP-UX server (L-class, PA-RISC with 11.23).

My question is- now that vg00 is extended onto the new disk with lvol1-7 mirrored, how are new lvols to be created with remaining space?

If I use SAM, I don't see a way to specify that new lvols wind-up on primary or mirror device, and I'd assume at the minimum, after creation, I'd need to shell-out and -m them to the mirror device. I'm just concerned if SAM is going to put them on the mirror device or if it will only put them on the parent/original vg disk.

So what's the best way to add new lvols? Is there anyway SAM can be used (even if post-fix mirroring afterwards at the shell, which is fine). Or from the point of adding mirroring, do any and all new lvols need be added from the shell to specify the primary device?

Thank you in advance!

Re: Another HP-UX Mirroring Question

Torsten. — Sat, 22 May 2010 19:11:14 GMT

When using SAM you can select the the option for mirroring or not, but I always use the command line for such task for better control.

Re: Another HP-UX Mirroring Question

Stevereno_1 — Sat, 22 May 2010 19:21:57 GMT

If I select Mirror 1 in SAM, is SAM smart enough to use the other disk device?

I guess the part that is throwing me is that UX/Mirroring starts with extending a Volume Group across two disks. Initially, this is fine as all the lvols of interest happen to all be on the first physical disk.

After this extension, what's to stop SAM (or the command line for that matter) from putting any new lvols created on both (or either/or) the primary and mirror physical devices (i.e. linearly across the open space)? Or is SAM smart enough to know "Mirror = 1, so put lvol on device A, then mirror on device B if there are two devices for this vgroup).

I mean, if you simply START by extended a volume group across two devices, it'll usually span lvols across the two however it sees fit, no?

Re: Another HP-UX Mirroring Question

Torsten. — Sat, 22 May 2010 19:30:09 GMT

see man lvcreate:

...
-s strict
Set the strict allocation policy. Mirror copies of a logical extent can be allocated to share or not share the same physical volume or physical volume group. strict can have one of the following values:

y
Set a strict allocation policy. Mirrors of a logical extent cannot share the same physical volume. This is the default.

...

Per default the mirror copy must be on another disk.