On Wed, Jan 7, 2009 at 7:11 PM, Scott Carey <scott@xxxxxxxxxxxxxxxxx> wrote: > If you're stuck with a Dell, the Adaptec 5 series works, I'm using 5085's in > a pair and get 1200 MB/sec streaming reads best case with 20 SATA drives in > RAID 10 (2 sets of 10, software raid 0 on top). Of course, Dell doesn't > like you putting in somebody else's RAID card, but they support the rest of > the system when you add in a third party PCIe card. > Sure, they are a bit pricey, but they are also very good performers with > drivers for a lot of stuff, including OpenSolaris. I tested a PERC 6 versus > this with the same drives, but only 10 total. The Adaptec was 70% faster > out of the box, and still 35% faster after tuning the linux OS read-ahead > and other parameters. Sequential read performance means precisely squat for most database loads. The dell stuff is ok....decent RAID 5 performance and mediocre raid 10. Unfortunately switching the disks to jbod and going software raid doesn't seem to help much. The biggest problem with dell hardware that I see is that overflowing the raid cache causes the whole system to spectacularly grind to a halt, causing random delays. To the OP, it looks like you are getting about 300 or so tps out of sdc (80% read), which is where I'm assuming the data is. I'm guessing most of that is random traffic. Here's the bad news: while this is on the low side for a 6 disk raid 10 7200 rpm, it's probably about what your particular hardware can do. I have some general suggestions for you: *) upgrade hardware: more/faster disks, etc *) disable fsync (dangerous!) can risk data loss, but maybe you have redundancy built in a different place. This will let linux reorganize i/o on top of what the hardware is doing. *) upgrade to postgres 8.3. Numerous efficiency advantages, and has the synchronous_commit setting, which is 'fsync lite'...most of the advantages and a lot less risk. *) tune the app merlin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
