For storage pools, TSM will create a thread (concurrent I/O ) for each of the storage pool volumes, if you have that many sessions going.
So again, if you have a lot of physical disks for the storage pools, you spread the storage pool volumes across those disks. However, in this case it's all problematic - if you are talking 1 big raid-5 array, and 1 channel, it's all very problematic. You will get a write penalty on the RAID-5, and the storage pool I/O will conflict with the log and DB I/O. So you need to think about how many TOTAL I/O operations you've got going on, and keep it down to a smaller number, maybe the number of physical disks in the RAID group, dunno. If you are connected to a Shark (IBM ESS) or EMC disk with GB of cache memory in front of the disk, you can pump a cazillion IO's/sec into those things - more than your Windows server can send, so it won't matter much. Anything less, I'd say if you are worried about performance, you should split off some of the physical disks into raid-1 for the DB. But, with only 1 channel, it's unclear whether that will help. You can find many, many permutations of this disscussion in search.adsm.org..... -----Original Message----- From: French, Michael [mailto:[EMAIL PROTECTED] Sent: Thursday, January 15, 2004 2:28 PM To: [EMAIL PROTECTED] Subject: Re: disk and db volume sizes I talked to a guy at IBM several months back and his suggestions were that you should analyze the number of concurrent sessions that you have going at anyone one time and create an equal number of DB volumes. I usual have about 20 concurrent backup sessions going during my various backup windows so I am in the process of breaking my DB volumes into smaller ones. He told me that this was a thread issue with how TSM talks to the DB volumes (hope I got that part right). As for the log volumes, I was told this is like a paging file, make one large one. If anyone at there has counter views, speak up now before I start tearing apart my systems! Michael French Savvis Communications IDS01 Santa Clara, CA (408)450-7812 -- desk (408)239-9913 -- mobile -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Joe Crnjanski Sent: Thursday, January 15, 2004 10:04 AM To: [EMAIL PROTECTED] Subject: disk and db volume sizes Hi Everyone, Does anybody know what is the optimum (best performance and reliability) size for disk pool and database volumes. Is it better to have one big volume (500GB example) or 5x100GB. Here we are talking around 1TB of RAID5 size on Win2k server. All volumes would reside on the same RAID 5 array and on 1 channel on IBM 4MX 160 RAID controller. Same question for db volumes; size of volume vs. number of volumes. Thanks, Joe Crnjanski Infinity Network Solutions Inc. Phone: 416-235-0931 x26 Fax: 416-235-0265 Web: www.infinitynetwork.com
