Hi Dave, On Mon, 2005-11-14 at 18:51 -0500, Dave Cramer wrote: > Joost, > > I've got experience with these controllers and which version do you > have. I'd expect to see higher than 50MB/s although I've never tried > RAID 5 > > I routinely see closer to 100MB/s with RAID 1+0 on their 9000 series OK, than there must be hope. > I would also suggest that shared buffers should be higher than 7500, > closer to 30000, and effective cache should be up around 200k In my current 8.1 situation I use shared_buffers = 40000, effective_cache_size = 131072 . > work_mem is awfully high, remember that this will be given to each > and every connection and can be more than 1x this number per > connection depending on the number of sorts > done in the query. I use such a high number because I am the only user querying and my queries do sorted joins etc. > fsync=false ? I'm not even sure why we have this option, but I'd > never set it to false. I want as much speed as possible for a database conversion that MUST be handled in 1 weekend (it lasts now, with the current speed almost 7 centuries. I may be off a millenium). If it fails because of hardware problem (the only reason we want and need fsync?) we will try next weekend until it finally goes right. What I can see is that only the *write* performance of *long updates* (and not inserts) are slow and they get slower in time: the first few thousand go relatively fast, after that PostgreSQL crawls to a halt (other "benchmarks" like bonnie++ or just dd'ing a big file don't have this behavior). I did notice that changing the I/O scheduler's nr_request from the default 128 to 1024 or even 4096 made a remarkable performance improvement. I suspect that experimenting with other I/O schedululers could improve performance. But it is hard to find any useful documentation about I/O schedulers. -- Groeten, Joost Kraaijeveld Askesis B.V. Molukkenstraat 14 6524NB Nijmegen tel: 024-3888063 / 06-51855277 fax: 024-3608416 e-mail: J.Kraaijeveld@xxxxxxxxxx web: www.askesis.nl ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
