the only thing I remember from working on a test using DB2 is that you need to carefully match the data read and write sizes to the XIV's sizes to make sure the reads and writes happen in 'one go' ... no double-taps to get or put data. that and making sure your fibre paths are separate (as always) from tape drives.
Many thanks! Bruce T. >>> Bruce T. Harvey AIX Network Engineer Remco Post <r.p...@plcs.nl> Sent by: "ADSM: Dist Stor Manager" <ADSM-L@vm.marist.edu> 09/29/10 07:47 AM Please respond to "ADSM: Dist Stor Manager" <ADSM-L@vm.marist.edu> To ADSM-L@vm.marist.edu cc Subject [ADSM-L] TSM and XIV Hi all, I'm currently testing TSM 5.5.4 on AIX 5.3 with an IBM XIV box. When I use dd or other tools to copy data off the disk to tape (LTO4), we get quite a good performance, 100 MB/s or better. Even when backing up data on the XIV via shared memory directly to tape, we're quite happy, we can read the data at over 100 MB/s for one backup job, and for over 200 MB/s for two jobs. But, when TSM uses the XIV for DISK volumes, we're not in a happy place, backing up data from one XIV to TSM with diskpool on another XIV, we get about 55 MB/s per backup job, best case. Both XIV boxes are otherwise completely idle. When migrating data of the diskpool to tape, it's the same, no matter what we do, we don't even get close to the LTO4 native performance, about 70 MB/s is the best I've seen, and usually it's less. The TSM server is at that time only running the migration, nothing else. The stragest thing we notice is that TSM seems to completely pause every so often, no disk i/o, no tape i/o no cpu utilization, nothing for about one second, and the it goes again. When I let two migration processes run, this is less obvious, because one process continues while the other one pauses. We've opened a hardware call with IBM to find out if there are any settings on the hdisks or HBAs that we need to change, and even though we did get some hints, and some performance improvement out of that, we fell that TSM should be able to do a lot better. Does anyone else have experience with XIV as a diskpool? and if so, what sort of performance do you see? -- Met vriendelijke groeten, Remco Post, PLCS The contents of this email are the property of PNC. If it was not addressed to you, you have no legal right to read it. If you think you received it in error, please notify the sender. Do not forward or copy without permission of the sender. This message may contain an advertisement of a product or service and thus may constitute a commercial electronic mail message under US Law. The postal address for PNC is 249 Fifth Avenue, Pittsburgh, PA 15222. If you do not wish to receive any additional advertising or promotional messages from PNC at this e-mail address, click here to unsubscribe. https://pnc.p.delivery.net/m/u/pnc/uni/p.asp By unsubscribing to this message, you will be unsubscribed from all advertising or promotional messages from PNC. Removing your e-mail address from this mailing list will not affect your subscription to alerts, e-newsletters or account servicing e-mails.
