Joni Yes Reed is correct there.
This is only one of 3 problems, your raid configuration on your sata disks. the size of your TSM attrigates. or the placements of diskvolumes versus the accual phicial disks. for instance if you have more than 2 volumes per phicial disk and you are doing backup on eatch volume you will hit a bottleneck on the I/O because of the head of the disk will be doing nothing more than jumping from one write operation to another. the same goes with read to tape. Kær kveðja / Best regards, Pétur Eyþórsson · Tæknilegur ráðgjafi eServer & Storage · Tivoli Advanced Storage Solutons Techical Expert · MCSE · SNIA Professional · SNIA FC-SAN Practitioner · IBM C AIX S · TSM CP · TSRM CP · TASS DP · IBM SAN P Sími/tel: +354 569-7700 · GSM: +354 863-0560 www.nyherji.is Leigh Reed <[EMAIL PROTECTED]> Sent by: "ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> 17.08.2005 16:17 Please respond to "ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> To ADSM-L@VM.MARIST.EDU cc Subject Re: [ADSM-L] AW: [ADSM-L] Migration Speed Has Plummeted Joni I missed the URL off the last post, so firstly, here it is http://www.redbooks.ibm.com/redbooks/pdfs/sg246638.pdf I don't think that there is a maximum number of volumes that can be configured in a primary storagepool with a devclass of disk and random. We have 25 volumes that are 35GB each in size, for a total of 875GB. But I must stress that this is on FastT disk which are FC. I have seen postings where people have considerably more volumes defined. However, as posts have said, the SATA disks are designed for their 'sequential' nature and I believe that the more concurrent reads/writes that you put through them, the performance degrades. You say that you have 1TB of SATA disk, but you don't mention the size/number of the disks. For example, if the 1TB was comprised of 4 x 250GB drives, it may well be worth only configuring 4 migration threads, to maximise the sequential nature of the disks. Ie 1 disk sequentially writing to one tape. Again, this is only theory, as I don't know that the internals of TSM will function in this way. Also, I haven't considered whether or not you have RAID'd the disks. You mention that it is EMC disk and I assume that it is from the CX range. It may well be worth speaking to EMC to ask if you can tune the performance of the controllers for the type of I/O that TSM is doing. Leigh -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Joni Moyer Sent: 17 August 2005 16:23 To: ADSM-L@VM.MARIST.EDU Subject: Re: [ADSM-L] AW: [ADSM-L] Migration Speed Has Plummeted Hi Leigh, I have brought in 1TB of SATA disk for random disk storage pools. Would you happen to know if there is a maximum number of volumes that can be defined per storage pool? If I have a disk pool that is 800GB, how many volumes should I have defined? What should the max. size of each volume be? If anyone has any ideas, please let me know. Thanks! ******************************** Joni Moyer Highmark Storage Systems Work:(717)302-6603 Fax:(717)302-5974 [EMAIL PROTECTED] ******************************** "Leigh Reed" <[EMAIL PROTECTED] > To Sent by: "ADSM: ADSM-L@VM.MARIST.EDU Dist Stor cc Manager" <[EMAIL PROTECTED] Subject .EDU> Re: AW: [ADSM-L] Migration Speed Has Plummeted 08/17/2005 10:39 AM Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED] .EDU> Joni The following URL is to the TSM V5.3 Technical Guide Redbook. If you go to section 3.4.6, it discusses some changes in TSM 5.3 that lend themselves to 'disk only backups' Obviously, if you're not at 5.3 yet, then they may not be of use to you. I personally would consider SATA disk as a possible replacement to sequential tape, but I would still use good quality fast disk as traditional 'random' disk pool to stage the nightly backups. I think that it is widely recognised that significantly 'slicing up' the diskpool into a large number of smallish volumes, greatly improves performance (certainly on the backup). I believe that this is because of the 'multi-threaded' nature of TSM. I would imagine that the config for the best performance of SATA disk as random TSM backuppool, would be to configure each SATA disk as a single TSM volume within the backuppool and ensure that you have enough SATA disks/backuppool volumes as you have sessions in at the same time. However, with SATA disk capacity increasing rapidly, it's not efficient to have a 100 x 250GB SATA disks (100 TSM volumes) sitting in your backuppool, that only ever get 10% utilised. I must state that this is just my opinion, I have no direct experience with SATA disks. Leigh
