On 4 February 2010 10:02, Amitabh Kant <amitabhkant@xxxxxxxxx> wrote: > On Wed, Feb 3, 2010 at 10:05 PM, Ivan Voras <ivoras@xxxxxxxxxxx> wrote: >> >> On 02/03/10 16:10, Amitabh Kant wrote: >>> >>> Hello >>> >>> I have a server dedicated for Postgres with the following specs: >>> >>> RAM 16GB, 146GB SAS (15K) x 4 - RAID 10 with BBU, Dual Xeon E5345 @ >>> 2.33GHz >>> OS: FreeBSD 8.0 >> >> If you really do have "heavy read and write" load on the server, nothing >> will save you from the bottleneck of having only 4 drives in the system (or >> more accurately: adding more memory will help reads but nothing helps writes >> except more drivers or faster (SSD) drives). If you can, add another 2 >> drives in RAID 1 and move+symlink the pg_xlog directory to the new array. > > Can't do anything about this server now, but would surely keep in mind > before upgrading other servers. Would you recommend the same speed > drives(15K SAS) for RAID 1, or would a slower drive also work here (10K SAS > or even SATA II)? Again, it depends on your load. It would probably be best if they are approximately the same speed; the location of pg_xlog will dictate your write (UPDATE / INSERT / CREATE) speed. Writes to your database go like this: the data is first written to the WAL (this is the pg_xlog directory - the transaction log), then it is read and written to the "main" database. If the main database is very busy reading, transfers from WAL to the database will be slower. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
