On 05/03/12, Craig James (cjames@xxxxxxxxxxxxxx) wrote: > On Sun, Mar 4, 2012 at 10:36 AM, Rory Campbell-Lange < > rory@xxxxxxxxxxxxxxxxxx> wrote: > > > We do have complex transactions, but I haven't benchmarked the > > performance so I can't describe it. Few of the databases are at the many > > million row size at the moment, and we are moving to an agressive scheme > > of archiving old data, so we hope to keep things fast. > > > > However I thought 15k disks were a pre-requisite for a fast database > > system, if one can afford them? I assume if all else is equal the 1880 > > controller will run 20-40% faster with 15k disks in a write-heavy > > application. Also I would be grateful to learn if there is a good reason > > not to use 2.5" SATA disks. > > Without those benchmarks, you can't really say what "fast" means. There > are many bottlenecks that will limit your database's performance; the > disk's spinning rate is just one of them. Memory size, memory bandwidth, > CPU, CPU cache size and speed, the disk I/O bandwidth in and out, the disk > RPM, the presence of a BBU controller ... any of these can be the > bottleneck. If you focus on the disk's RPM, you may be fixing a bottleneck > that you'll never reach. > > We 12 inexpensive 7K SATA drives with an LSI/3Ware 9650SE and a BBU, and > have been very impressed by the performance. 8 drives in RAID10, two in > RAID1 for the WAL, one for Linux and one spare. This is on an 8-core > system with 12 GB memory: > > pgbench -i -s 100 -U test > pgbench -U test -c ... -t ... > > -c -t TPS > 5 20000 3777 > 10 10000 2622 > 20 5000 3759 > 30 3333 5712 > 40 2500 5953 > 50 2000 6141 Thanks for this quick guide to using pgbenc. My 4-year old SCSI server with 4 RAID10 disks behind an LSI card achieved the following on a contended system: -c -t TPS 5 20000 446 10 10000 542 20 5000 601 30 3333 647 These results seem pretty lousy in comparison to yours. Interesting. -- Rory Campbell-Lange rory@xxxxxxxxxxxxxxxxxx Campbell-Lange Workshop www.campbell-lange.net 0207 6311 555 3 Tottenham Street London W1T 2AF Registered in England No. 04551928 -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
