In response to David Brain <dbrain@xxxxxxxxxxxxx>: > > Thanks for the response. > Bill Moran wrote: > > In response to David Brain <dbrain@xxxxxxxxxxxxx>: > >> I recently migrated one of our large (multi-hundred GB) dbs from an > >> Intel 32bit platform (Dell 1650 - running 8.1.3) to a 64bit platform > >> (Dell 1950 - running 8.1.5). However I am not seeing the performance > >> gains I would expect > > > > What were you expecting? It's possible that your expectations are > > unreasonable. > > Possibly - but there is a fair step up hardware performance wise from a > 1650 (Dual 1.4 Ghz PIII with U160 SCSI) to a 1950 (Dual, Dual Core 2.3 > Ghz Xeons with SAS) - so I wasn't necessarily expecting much from the > 32->64 transition (except maybe the option to go > 4GB easily - although > currently we only have 4GB in the box), but was from the hardware > standpoint. Ahh ... I didn't get that from your original message. > I am curious as to why 'top' gives such different output on the two > systems - the datasets are large and so I know I benefit from having > high shared_buffers and effective_cache_size settings. Have you done any actual queries on the new system? PG won't use the shm until it needs it -- and that doesn't occur until it gets a request for data via a query. Install the pg_bufferstats contrib module and take a look at how shared memory is being use. I like to use MRTG to graph shared buffer usage over time, but you can just do a SELECT count(*) WHERE NOT NULL to see how many buffers are actually in use. > > Provide more information, for one thing. I'm assuming from the top output > > that this is some version of Linux, but more details on that are liable > > to elicit more helpful feedback. > > > Yes the OS is Linux - on the 1650 version 2.6.14, on the 1950 version 2.6.18 -- Bill Moran Collaborative Fusion Inc. wmoran@xxxxxxxxxxxxxxxxxxxxxxx Phone: 412-422-3463x4023 **************************************************************** IMPORTANT: This message contains confidential information and is intended only for the individual named. If the reader of this message is not an intended recipient (or the individual responsible for the delivery of this message to an intended recipient), please be advised that any re-use, dissemination, distribution or copying of this message is prohibited. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. E-mail transmission cannot be guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. The sender therefore does not accept liability for any errors or omissions in the contents of this message, which arise as a result of e-mail transmission. ****************************************************************
