Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de> wrote:
> 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).

No, as I said, the recovery does not touch a LV/filesystem (in vg00)
if you do not include that filesystem in your recovery tape. So you do
not have to recover the database.

> 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.

What I meant there is the vgcfgrestore which the (Ignite-UX) recovery
process does, not one which you do yourself. So, as far as your
application data LV/filesystem is concerned, it does not matter if the
recovery provess does a vgcfgrestore or not.