Frank Slootweg <this@ddress.is.invalid> writes:

> Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de> wrote:
> [deleted]
> > (I know what the disadvantages of two VGs on one disk are, but I'm
> > hoping that Ignite-UX' recovery tapes will be able to restore just
> > that (system) partition on the disk without touching the other VG
> > (application data). Would it work?)
>
> Can't you just put the application data in its own LV(s)? If you keep
> the recovery tapes up-to-date with any changes in the (vg00) LVM layout,
> a restore should not touch the (application data) *LV(s)* in any way.

Hi,

well if HP-UX patches wouldn't make the systems unbootable from time to time,
and if recovery media really would be able to revive an unbootable system,
this would not be a problem at all. However I had had unbootable systems that
had to be recovered by installing the recovery tape. As this is downtime, you
try to keep that as short as possible. If you have all your application data
on its own VG (we are talking about a database application >50GB), then just
recover the root/boot VG, and then import the other VG, and all your
application data is untouched (the OS will lack most recent changes of
course). If you have all in one VG, recovering means you also have to recover
the database data which takes much longer to create a recovery media and to
restore it. In addition Ignite-UX does not support recovery media >4GB (no
double-layer DVD, no media change).

So I guessed that the LVM should only touch the device (e.g. partition instead
of whole disk) and having a PV in a partition (multiple PVs on one disk) would
work. This would assume recovery would not touch the partition table. This
also seems to be not true.


> I.e. a vgcfgrestore(1M) of an *unchanged* VG does not touch any LVs in
> that VG.

Yes, but the type of problem that can be fixed using vgcfgrestore is not the
type of problem I'm afraid of.

Regards,
Ulrich