If you lose all copies of a single database volume, then it's recovery time. If
your recovery log is in roll-forward mode *and* it is still intact, you can
actually restore the individual database volume (see RESTORE DB in the Admin
Reference). Otherwise you'll have to restore the entire database.
As to the other question in this post, performance is not a forte of mine, but
I'll hazard a guess: since the ADSM database is accessed randomly, spreading
the database across multiple physical volumes might help performance. Maybe
spread the primary copies across half the disks, and the mirrors across the
other half. On the other hand, the recovery log is sequential in nature, so
it's probably better off being stored contiguously (mirroring on a separate
disk).
Just my $0.02 (say, what *can* you buy for 2 cents nowadays?),
Andy
Andy Raibeck
IBM Storage Systems Division
ADSM Client Development
e-mail: storman AT us.ibm DOT com
ADSM-L AT VM.MARIST DOT EDU on 07/27/98 04:09:28 PM
Please respond to ADSM-L AT VM.MARIST DOT EDU
To: ADSM-L AT VM.MARIST DOT EDU
cc:
Subject: FW: database volumes
I'd like to add something to this question. Anyone know what happens
if you loose all copies of a single databse volume?
Thanks,
Hilary Whitehead
IBM Global Services
> -----Original Message-----
> From: Brown, Ed [SMTP:EXBrown AT SNOPUD DOT COM]
> Sent: Monday, July 27, 1998 2:55 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: database volumes
>
> In our current configuration we have a single large Logical
> Volume spread over 10x4.5GB SSA drives. We have 8x500MB database
> volumes
> for our ADSM database. We are upgrading ADSM and moving to a new
> server.
> We have 8x9.1GB SSA drives. We have decided to create a logical volume
> on each disk so that we can easily manage the location of our storage
> volumes in relation to the physical disks.
>
> My question is this....
>
> If I have 6x1GB database volumes, would it be more prudent to
> (1) Dedicate 2 physical drives to DBvolumes and place all six of the
> DBvolumes on a single drive. Then use ADSM to mirror them on a
> different drive? Or (2) should I spread DBvolumes around onto all of
> the
> drives in the Volume Group?
>
> Basically, what is the trade off by spreading the DBvolumes
> around on all of the disks, rather then containing them on 2 disks,
> one
> for the DB and one for the mirror.
>
>
>
> Ed Brown
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