Re: Multiple Database clusters on 1 server: good practice or not advisable?

Paul,

Others may have better advice, but my $0.02 worth ...

It is certainly possible to run several instances of postgres on one server (at least on *NIX, don't know about Windoze). This is about postgres 7.4 and 8.1.

We have some servers that have a several different postmasters running; the hope being that if one gets clobbered the others won't be directly effected. You have to make sure you have a lot of RAM so both can have enough for the IPCS processes and leave enough for the OS to have a healthy cache. If you run short on memory you get start to see disk thrashing and such issues. Each postmaster has its own pools of memory for connections, etc. and you can configure them differently if you need to. They'll be writing to different logs which can make solving problems easier.

We also have some servers with only one postmaster running, but it has several databases within it. If one issue takes down the postmaster then both databases go down, obviously. All of the databases share in the number of connections allowed, and will write to the same log file (I think -- if I am wrong, someone, please correct me!).

In general anything bad enough to really hammer one database/instance will have a deleterious effect on other users on the server, no matter how you configure it. But we've had no problems in back-office stuff running multiple instances on one box (2-3, but occasionally more); some of these get heavy, albeit periodic use. We also have some runtime applications with two different postmasters on one box and have had no problems, but they tend to be lightweight in terms of volume and total # of connections, etc. Out heavy runtime servers we tend to have databases sharing the same instance.

YMMV, HTH, etc., yadda yadda

Greg Williamson
DBA
GlobeXplorer LLC

-----Original Message-----
From: pgsql-admin-owner(at)postgresql(dot)org on behalf of Paul Schluck
Sent: Fri 10/13/2006 2:23 AM
To: pgsql-admin(at)postgresql(dot)org
Cc:
Subject: [ADMIN] Multiple Database clusters on 1 server: good practice or not advisable?

Hi,

We want to use PostgreSQL at our company for several distinct applictions.
As a newby to PostgreSQL, I wonder if it would be wise to make a separate
database cluster for eacht application. As I understand it, this would give
me the possibility administer each application seperately. For instance some
applications only need to be up from 8-17, so we can easily make off-line
backups, while others need to be up 24x7 and we have to make on-line
backups.

All comments are appreciated.

Kind regards,

Paul.

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