We run multiple postmasters because we can shutdown one postmaster/database without affecting the other postmasters/databases. Each database is a division in our company. If we had everything under one postmaster if something happened to the one the whole company would be down. -----Original Message----- From: pgsql-performance-owner@xxxxxxxxxxxxxx [mailto:pgsql-performance-owner@xxxxxxxxxxxxxx] On Behalf Of Dave Cramer Sent: Thursday, April 05, 2007 4:01 PM To: John Allgood Cc: 'Jeff Frost'; pgsql-performance@xxxxxxxxxxxxxx Subject: Re: [PERFORM] High Load on Postgres 7.4.16 Server On 5-Apr-07, at 3:33 PM, John Allgood wrote: > The hard thing about running multiple postmasters is that you have > to tune > each one separate. Most of the databases I have limited the max- > connections > to 30-50 depending on the database. What would reasonable values for > effective_cache_size and random_page_cost. I think I have these > default. > Also what about kernel buffers on RHEL4. > random_page_cost should be left alone Why do you run multiple postmasters ? I don't think this is not the most efficient way to utilize your hardware. Dave > Thanks > > -----Original Message----- > From: pgsql-performance-owner@xxxxxxxxxxxxxx > [mailto:pgsql-performance-owner@xxxxxxxxxxxxxx] On Behalf Of Jeff > Frost > Sent: Thursday, April 05, 2007 3:24 PM > To: John Allgood > Cc: pgsql-performance@xxxxxxxxxxxxxx > Subject: Re: [PERFORM] High Load on Postgres 7.4.16 Server > > On Thu, 5 Apr 2007, John Allgood wrote: > >> Hello All >> >> I sent this message to the admin list and it never got through so I >> am trying the performance list. >> We moved our application to a new machine last night. It is a Dell >> PowerEdge 6950 2X Dual Core. AMD Opteron 8214 2.2Ghz. 8GB Memory. The >> machine is running Redhat AS 4 Upd 4 and Redhat Cluster Suite. The >> SAN is > an >> EMC SAS connected via fibre. We are using Postgres 7.4.16. We have > recently >> had some major hardware issues and replaced the hardware with >> brand new > Dell >> equipment. We expected a major performance increase over the previous > being >> the old equipment was nearly three years old >> I will try and explain how things are configured. We have 10 >> separate postmasters running 5 on each node. Each of the >> postmasters is a >> single instance of each database. Each database is separated by >> division > and >> also we have them separate so we can restart an postmaster with >> needing to >> restart all databases My largest database is about 7 GB. And the >> others > run >> anywhere from 100MB - 1.8GB. >> The other configuration was RHEL3 and Postgres 7.4.13 and Redhat >> Cluster Suite. The application seemed to run much faster on the older >> equipment. >> My thoughts on the issues are that I could be something with the OS >> tuning. Here is what my kernel.shmmax, kernel.shmall = 1073741824. Is > there >> something else that I could tune in the OS. My max_connections=35 and > shared >> buffers=8192 for my largest database. > > John, > > Was the SAN connected to the previous machine or is it also a new > addition > with the Dell hardware? We had a fairly recent post regarding a > similar > upgrade in which the SAN ended up being the problem, so the first > thing I > would do is test the SAN with bonnie-++ and/or move your > application to use > a > local disk and test again. With 8GB of RAM, I'd probably set the > shared_buffers to at least 50000...If I remember correctly, this > was the > most > you could set it to on 7.4.x and continue benefitting from it. I'd > strongly > > encourage you to upgrade to at least 8.1.8 (and possibly 8.2.3) if > you can, > as > it has much better shared memory management. You might also want > to double > check your effective_cache_size and random_page_cost to see if they > are set > to > reasonable values. Did you just copy the old postgresql.conf over? > > This is the beginning of the thread I mentioned above: > > http://archives.postgresql.org/pgsql-performance/2007-03/msg00104.php > > -- > Jeff Frost, Owner <jeff@xxxxxxxxxxxxxxxxxxxxxx> > Frost Consulting, LLC http://www.frostconsultingllc.com/ > Phone: 650-780-7908 FAX: 650-649-1954 > > ---------------------------(end of > broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.446 / Virus Database: 268.18.26/746 - Release Date: > 4/4/2007 > 1:09 PM > > > > ---------------------------(end of > broadcast)--------------------------- > TIP 4: Have you searched our list archives? > > http://archives.postgresql.org ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 268.18.26/746 - Release Date: 4/4/2007 1:09 PM
