On Sat, Nov 22, 2008 at 7:18 AM, Glyn Astill <glynastill@xxxxxxxxxxx> wrote: > Hi chaps, > > I've had this old card sitting on my desk for a while. It appears to be a U160 card with 128Mb BBU so I thought I'd wang it in my test machine (denian etch) and give it a bash. > > I set up 4 36Gb drives in raid 0+1, but I don't seem to be able to get more than 20MB/s write speed out of it for large files (2XRAM usual tests with dd from dev/zero). I don't expect anything great, but I thought it'd do a little better than that. You really have two choices. First is to try and use it as a plain SCSI card, maybe with caching turned on, and do the raid in software. Second is to cut it into pieces and make jewelry out of it. Anything before the Perc 6 series is seriously brain damaged, and the Perc6 brings the dell raid array line squarly in line with a 5 year old LSI megaraid, give or take. And that's being generous. > I've tried writeback and write through modes, tried changing cache flush times, disabled and enabled multiple PCI delayed transactions, all seem to have little effect. Yeah, it's like trying to performance tune a yugo. > Finally I decided to wave goodbye to Dell's firmware. LSI has it down as a MegaRAID 493 elite 1600, so I flashed it with their latest firmware. Doesn't seem to have helped either though. Does it have a battery backup module? Often you can't really turn on write-back without one. That would certainly slow things down. But you should certainly expect > 20 M/s on a modern RAID controller writing out to a 4 disk RAID10 > Has anybody else used this card in the past? I'm wondering if this is a driver issue, or if the card is and always was just crap? If so I'll proabably try sw raid on it instead. It's pretty much a low end card. Look into modern LSI, Areca, or Escalade/3Ware cards if you want good performance. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
