RE: Restore on V5R4 after upgrade painfully slow

Hi David

Given the comment about 300 libraries every 5.5 hours, it seems that the source system had a lot of libraries and objects versus a lot of data - does that sound right ? Don't forget that a restore will complete different libraries at different rates. It's not unusual for the biggest libraries to take the majority of the restore time. The larger libraries always seem to be clumped together.

It's been my experience that the length of a restore is pretty difficult to predict. The last 2 upgrades I have done (both a Previous Release to Current Release) the restore was quicker than the save, but I have done others where this was not the case - it depends on lots of things: tape media; disk arms; iop; tape controller; memory; etc.

There was a rule of thumb at one stage that a restore was about twice as long as a save, and while this is a useful benchmark it is not that accurate these days but is worth keeping in mind.

I have observed over the years that restoring lots of objects and lots of small files or multi-member files was comparatively slower than for the same amount of data tied up in one large file. If the system is entirely made up of small objects then the object creation process during the restore seems to impact the restore time more than would be expected.

Given your 300 libraries comment I'd be more prepared to guess that it was the number of objects that is causing the the delay compared to the access path situation. But that's just a guess.

Something else to think about anyway.

Regards
Evan Harris



-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of David Gibbs
Sent: Tuesday, 10 February 2009 6:54 a.m.
To: Midrange Systems Technical Discussion
Subject: Restore on V5R4 after upgrade painfully slow

I'm posting this for a co-worker ...

I'm doing a migration from a 9406-820 to a 9408-M25. I’m doing a Previous Release to Current Release Migration. I’m following the procedure in the V5R4 Backup and Recovery guide chapter 14.

I did a full system backup of the 9406-820 to a 3581 Ultrium 2 tape drive on a 2749 controller card. The backup took 4 hours. After the backup IBM moved the 2749 card and installed it in a 595 expansion unit and connect the 3581 Ultrium 2. We restored the user profiles and cfg information with no problems. We then started the 'RSTLIB savlib(*nonsys) dev(tap02 option(*new) alwobjdif(*all) mbrobt(*all) frcobjcvn(*no) endopt(*leave) omitobj(qofc)'. I calculated that the libraries consist of about 50GB. The restore is restoring about 300 libraries every 5.5 hours. It is running crazy slow and we can’t figure out why.

Any thoughts?

Thanks!

david