"ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> wrote on 06/20/2006 03:05:47 PM:
> John Monahan a écrit : > > >>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. > > > > > > > > > I remember that it's some limitation with DISK devclass for restore > purpose. It was a good IBM presentation about disk oriented backup with > good advice but I don't succeed to find the URL (TapelessTSM). All the restores will be from tape. This is a traditional diskpool, that gets emptied out to tape each night so the data doesn't stay on disk for more than a few hours. This particular customer has over 1TB to backup nightly, and not that much fibre space available, so SATA it is.
