Can you provide a little more information? I would like to know:
1. What kind of disk subsystem are you restoring the data to?
2. How many disks, and what kind of disks are they?
3. How is the database laid out database volume wise?
4. Does the disk have write cache behind it?
5. What kind of controller do you have for the disk subsystem?At 07:23 PM 1/20/2005 -0600, you wrote:
TSM 5.1.9.0 on AIX 5.2 ML4; DLT8000 media on SCSI
Why do TSM database restores take so much longer than the backups? Our system backs up our 24 GB database to DLT in about 50 minutes with a sustained rate of 11 MB/s reported by topas.
Tonight I'm performing a database restore. It is occurring at an average rate of less than 1 MB/s with rare peaks no higher than 6 MBs. At times the rate is as low as 300 KB/s.
I realize the system is writing data to disk rather than reading so its not doing as much caching, but these are new disks and I've seen them stream write at better than 25 MB/s on the inner edge and as fast as 50 MB/s on the outer edge. So I doubt the disk is the problem.
This restore has been running for almost 2-1/2 hours now and is about 90% complete.
This is the fourth or fifth time I've restored the TSM database in the seven years I've operated the system. I have never seen database restores exceed 1/3 the backup rate - sustained - on two different servers, three different media and going back to ADSM 3.1.
Just curious.
Tab Trepagnier TSM Administrator Laitram, L.L.C.
Dave Canan TSM Performance IBM Advanced Technical Support [EMAIL PROTECTED]
