Be careful of your copypool reclamations with the disk cache turned on!! There is a BIG performance hit on reclamation when the primary copy of the file is on a DISK direct access storage pool. Then the MOVESIZETHRESH and MOVEBATCHSIZE values are thrown out the window and the files are processed one at a time.
What I've done to relieve the restore times is to not MIGRATE the disk pools until the end of the day. That way restoring from last night is quick. I had a client where they wanted CACHE=YES on a 60GB disk pool. The offsite copypool reclamation ran for 2-days! Changed it so that migration started at 5:00pm and nobody complained about restore times. Bill Boyer DSS, Inc. -----Original Message----- From: ADSM: Dist Stor Manager [mailto:ADSM-L@;VM.MARIST.EDU]On Behalf Of Steve Schaub Sent: Thursday, October 31, 2002 5:59 AM To: [EMAIL PROTECTED] Subject: Re: Tape drive recomendations This is one reason I am looking into some of the new, cheaper ATA-based disk arrays. 98% of restores come from the last few versions, so if you can size the diskpool large enough (and turn caching on) that you rarely need to go to tape, restores scream. Some of the initial prices I am seeing are < $10k per TB. It's not SSA, but for a diskpool it might be fast enough. -----Original Message----- From: [EMAIL PROTECTED] Sent: Wednesday, October 30, 2002 10:15 PM To: UFL.EDU.asr; VM.MARIST.EDU;.ADSM-L Subject: Re: Tape drive recomendations 2 => On Wed, 30 Oct 2002 16:42:14 -0600, "Coats, Jack" <[EMAIL PROTECTED]> said: > From my fox hole, LTO works great, but in some ways it is 'to big'. > The spin time on the tapes is measured as about 3 minutes to rewind > and unmount a tape. Meaning if you have to scan down a tape to > restore a file it can be a while. Very fast tapes tend to be small, > so it is a real tradeoff. > Speed of restore is starting to be a factor here and I have seen > several posts where that is becoming more of an issue at many sites. > But the architecture of TSM that makes it great, also gets in the way > of high speed restores, unless you have lots of slots in a large > library for a relatively small number of clients (co-location and/or > backup sets - for theses many smaller tapes might be better, but I > digress). Our call on this is congealing: Use the LTO for less-often-read storage. i.e.: copy pools. If we can have primary pools on 3590s, we can get up to 60G raw on the -K volumes. That seems plenty at the moment. We can use the 200G-raw (coming soon!) LTO volumes for copies, and read from them correspondingly less often. LTO drives are, at the very least, a cheap way to increase your drive count. - Allen S. Rout
