just beeing curious: does your SATA controller and disks support NCQ/TCQ and ist either of them enabled? Is write cache on Disks enabled?
I am only extrapolating from SCSI experiences - command queuing and disk write cache can slow-down the raid (if both inactive) Juraj > -----Ursprüngliche Nachricht----- > Von: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] Im > Auftrag von John Monahan > Gesendet: Dienstag, 20. Juni 2006 21:35 > An: ADSM-L@VM.MARIST.EDU > Betreff: Re: TSM diskpool on SATA > > > Did you do any FILE devclass work? It sounds as though > your miserable > > performance was head thrashing, which we'd get in multiple LV DISK > > devclasses, and also in FILE devclasses. Darn. :) > > No I was using a DISK devclass, but I'm almost positive it > wouldn't have made any difference with FILE devclasses. Some > of the LUNs were faster than others (first ones in the RAID > group created) and as soon as I was writing to more than one > at a time my performance would tank even further, which > shouldn't be any different had I used FILE devclasses. I > would have tried file devclasses with more time for > performance reasons, but I had spent too much time on it > already and the 150 MB/sec writes for my diskpool was > adequate for my needs and outpaced the capabilities of my > single Gigabit network connection to the TSM server, so I moved on. > > Hundreds of LVs with FILE devclasses on fibre disks would > probably do exactly what you are looking for and provide > excellent performance. SATA just isn't good enough at > multiple, simultaneous I/Os to the same set of disks yet. >