The original poster said his disk pool had CACHE=YES turned on. So for a time a backed up file could reside in 3-different places....disk pool cache..onsite tape..offsite tape. Normally when you think of reclamation it is a tape-to-tape process, so I/we were generalizing.
The problems is that when the primay copy of the file is on a random access disk storage pool, TSM does not use the MOVEBATCHSIZE and MOVESIZETHRESH parameters to 'batch' the transactions. The reclamation process moves/reclaims 1 file..updates the DB....moves another file...updates the DB....etc.etc... When CACHE=YES is on, then TSM will use the primary location with the best performace...DISK. Even though the file is on the sequential onsite tape media. CACHE=YES is good for restore performance, but when the storage pool fills up during client backups, you have to overhead of TSM deciding which CACHE'd files to throw away, throwing then away and then accepting the new backup data. A process we use is to do all the storage pool backup first thing in the morning after the client backups are complete, but not do the migration until later in the afternoon. This way last nights' backup data is still on disk for restore performance, but then moved off before the next nights' backups start. We've found that a lot of the onsey-twosy restores are because the use hosed up his file today and needs it restored from last nights' backup. This way it comes from disk, but you don't have the CACHE=YES overhead and performance hit for reclamation. Bill Boyer DSS, Inc. "Backup my harddrive?...How do I put it in reverse??" - ?? -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED]]On Behalf Of Vos, F (Freek) Sent: Thursday, August 15, 2002 12:08 PM To: [EMAIL PROTECTED] Subject: Re: Bad performance from tape to tape Hi Bill, Reclamation is not only a tape to tape copy. The changes to the TSM database are they holding down your speed ? The amount of tape mounts, are there many ? Do the disks and the tapeunits share the same SCSI adapter ? Groet, Freek. -----Original Message----- From: Bill Boyer [mailto:[EMAIL PROTECTED]] Sent: donderdag 15 augustus 2002 17:15 To: [EMAIL PROTECTED] Subject: Re: Bad performance from tape to tape The tape-to-tape operation that is adversely affected is reclamation. If the primay location of a file is in a random access disk pool, then TSM does not 'batch' the files together. Each transaction is a single file. The primary location can be a disk sequential access pool, but not random access. We originally came across this with DIRMC. We had the primary a DISK pool and then only created the copypool. The reclamation on the copypool tapes used to take days. Opened a PMR with Tivoli and got the 'working as designed' answer. Bill Boyer DSS, Inc. -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED]]On Behalf Of Joe Pendergast Sent: Thursday, August 15, 2002 9:36 AM To: [EMAIL PROTECTED] Subject: Re: Bad performance from tape to tape Is the disk pool cached? I ran into a situation where the disk pool cache instead of tape was being used. This slowed my LTO drives to a crawl during certain operations. I now varyoff the disk pools before I run the process with expected results Don't forget to vary them back on at the end.. Note: the disk pool cache is a great help in restore time, but it can adversely the affect of what should be a tape to tape process. Halvorsen Geirr Gulbrand <[EMAIL PROTECTED]> on 08/15/2002 03:00:23 AM Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] cc: (bcc: Joseph Pendergast/Corona/Watson) Subject: Bad performance from tape to tape Hi All, I have a performance problem when doing Space-Reclaamtion, or backup storage pool, when TSM is copying data from one tape drive to the other. Environment: Windows 2K server, TSM 4.2.1.15. Library, Compaq MSL5026, with 2 SDLT drives (Single Module Library). SCSI Controller, Compaq 64-bit/66Mhz Dual Channel Wide Ultra3 SCSI Adapter (Compaq version of Adaptec 39160) Moving data from Disk to Tape runs with expected speed (8-10 MB/s). >From Tape to tape speed is around 2MB/s. (50GB takes about 7-8hours.) Does anyone know why? It is killing my daily operations. Mvh Geirr G. Halvorsen TSM Enterprise Backup Specialist WMdata Danmark A/S ================================================================== De informatie opgenomen in dit bericht kan vertrouwelijk zijn en is uitsluitend bestemd voor de geadresseerde. Indien u dit bericht onterecht ontvangt wordt u verzocht de inhoud niet te gebruiken en de afzender direct te informeren door het bericht te retourneren. ================================================================== The information contained in this message may be confidential and is intended to be exclusively for the addressee. Should you receive this message unintentionally, please do not use the contents herein and notify the sender immediately by return e-mail. ==================================================================
