I/O, I/O, it's all about I/O..... and IT DEPENDS on your hardware. The key here is that when you have the DB or a storage pool split into multiple "volumes", TSM will start multiple I/O operations to the DB or storage pool. You can use that to your advantage to improve performance, or carry it to such and extreme that it hurts your performance.
If you are talking physical disk: >> when you put many DB or storage pool "volumes" on one disk, you can get multiple I/O's in flight, all trying to access the same physical disk. The disk heads get yanked back and forth from one volume location to another, and that slows you down. If you are talking ESS, that is a whole different animal. >> The "volumes" you create are really split across many physical disks inside the ESS and there is a LOT of cache in the box that buffers I/O and makes it asynchronous, so you don't have to worry much about the performance hit caused by physical head movement. If you are talking non-ESS RAID, that is different still, as every vendor's implementation is a little different. >> With simple RAID implementations on arrays made up of a few disks you can get a performance penalty on WRITE; BUT if the vendor has enough RAM in the box to buffer the I/O, you see less of an impact. In your case, I expect the objective is to get your DB spread across those ESS loops, more than specifically getting you out of a single filesystem. That spreads your I/O out to get the max advantage of the hardware. SO IT DEPENDS, you will get different answers about performance and disk configuration, and there are sometimes multiple ways to do it, depending on your hardware and the problem you are trying to solve. ************************************************************************ Wanda Prather The Johns Hopkins Applied Physics Lab 443-778-8769 [EMAIL PROTECTED] "Intelligence has much less practical application than you'd think" - Scott Adams/Dilbert ************************************************************************ -----Original Message----- From: Thach, Kevin [mailto:[EMAIL PROTECTED]] Sent: Friday, November 22, 2002 9:53 AM To: [EMAIL PROTECTED] Subject: Re: Relocating TSM DB (storage) Funny you should mention that. We have been working with IBM ATS support about poor performance issues with our TSM config, and they say that our problem is because we have all 37 volumes in one AIX logical volume/filesystem. They have had us create 32 new AIX logical volumes/filesystems (don't need 37 because our db is not very full after running CLEANUP BACKUPGROUPS), each with a 1GB TSM DBvol inside, all of which are on separate ESS loops. They said the smaller DB volumes are better! Argghh!! -----Original Message----- From: Robert L. Rippy [mailto:[EMAIL PROTECTED]] Sent: Friday, November 22, 2002 9:35 AM To: [EMAIL PROTECTED] Subject: Re: Relocating TSM DB (storage) Yes, you are correct. Create the new DB's and extend the DB and then delete the old DB's. The data will migrate over to the new extended space. Any reason you had 37 1GB volumes for your DB's. IBM told me not to really go over 10 volumes on your DB and to be sure they aren't on the same drive if you can help it. I would suggest that if you could, create 5 8GB new volumes for a total of 40GB and move the DB over to the new 8GB partitions. Thanks, Robert Rippy From: "Thach, Kevin" <[EMAIL PROTECTED]> on 11/22/2002 09:30 AM Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] cc: Subject: Relocating TSM DB (storage) I am wanting to move our TSM DB which is currently on ESS, and has 37 1GB dbvolumes, to another set of ESS disk. If I define the new dbvolumes on the new disks, do I then just extend the db, and then do a del dbvol on the old ones? Does the delete make the data migrate over? Do I have to do a reduce db for any reason before I do the delete dbvol? Can I do the delete with the server up and running? Thanks This E-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the Individual(s) named above. If you are not the intended recipient of this E-mail, or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that any dissemination or copying of this E-mail is strictly prohibited. If you have received this E-mail in error, please immediately notify us at (865) 374-4900 or notify us by E-mail at [EMAIL PROTECTED] This E-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the Individual(s) named above. If you are not the intended recipient of this E-mail, or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that any dissemination or copying of this E-mail is strictly prohibited. If you have received this E-mail in error, please immediately notify us at (865) 374-4900 or notify us by E-mail at [EMAIL PROTECTED]