We run ADSM servers on Solaris, but with 3570 tapes.
My personal experience is that the speed of the restore DB
depends on the number of mirrors. Restoration for us in an
unmirrored situation is about 10-20% slower than the backup.
On top of that, if you have one mirror of the DB, then the
restore DB will take about double the time of an unmirrored
restoration. Two mirrors means about 3 times.
In addition, however, when the server starts up, it then
takes a big chunk of time to resync the mirrors. If it was
going to sync the mirrors anyway, you'd think restoring
a single copy of the DB would be enough.
Still, all of this does not add up to the times John is seeing.
Another issue is the number of tape mounts. On other DLT7000
tape drives, I've heard that a mount is about 2 minutes, and
a seek is about 1 minute. That means you've got 5 minutes
roundtrip per cartridge, plus data transfer time.
My final thought is to inquire how the disk that is receiving
the database is configured. If it is RAID 5 with Sun's default
controller cache (i.e. _way_ too small), then your write
performance to disk will be abysmal. My experience here is
that it's much better to go RAID 0, and let ADSM handle the
mirroring. At least, dramatically upgrade the size of the
cache RAM in the disk controller.
Rich
At 03:55 PM 9/15/99 -0500, John D. Schneider wrote:
>Greetings,
> I have a customer who has DLT7000 tape drives in a BreeceHill Q47
>library. They
>have ADSM 3.1.2.20 running under Solaris 2.6. Their ADSM database is
>about 8GB
>and takes about 50 minutes to backup.
> Twice now they have tried to restore the ADSM DB as part of a
>disaster recovery
>test (using DRM). Things go fine defining and installing the new DB,
>but the restore of
>the ADSM DB goes VERY slowly. It takes about 7 Hours to complete! I
>would have
>expected it to take 60-70 minutes maybe; a little slower than the
>backup, but not a lot
>slower.
> The system they are using for the test is faster and has 3GB ram, as
>much as the
>production system they are starting from. One thing that is different
>about the test system
>is that it has 3 DLT7000 drives on the same adapter, but I don't think
>that should matter
>much because the other two drives are idle during this time in the
>recovery.
> The restore is not hanging. It periodically gives it's messages
>that say how many
>pages have been restored, and the progress seems to be consistent, it is
>just VERY slow.
>
>Any ideas? Thanks in advance,
>
>John Schneider
>
>***********************************************************************
>* John D. Schneider Email: jdschn AT ibm DOT net * Phone: 314-349-4556
>* Lowery Systems, Inc.
>* 1329 Horan Disclaimer: Opinions expressed here are
>* Fenton, MO 63026 mine and mine alone.
>***********************************************************************
>
>
Richard C. Dempsey email: dempsey AT kodak DOT com
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