On Thu, 2007-03-29 at 15:13, Dmitry Koterov wrote: > No, but disks are about 120 MB/s speed, peak writes during CHECKPOINT > are only 20-30 MB/s, and there is no disk read activity at all, so - > no matter where the xlog resides. > > But now seems bgwriter tuning gets some effect, CHECKPOINT is running > faster (about 2-3 seconds instead of 10-15). It is still beats the > performance, but less. Well, I assume bgwriter isn't the only thing writing to those disks. Which would mean that your bgwriter output is random access not sequential. Which would mean putting pg_xlog on another set of drives where it wasn't competing with other postgresql (and system) processes for drive access would speed things up. Or getting a good battery backed RAID controller. That's the first step to building a fast db server if you're using built in storage. but I could be wrong or have misunderheard what you were saying.
