Re: Fault Tolerant Postgresql (two machines, two postmasters, one disk array)

>-----Original Message-----
>From: pgsql-general-owner@postgresql.org
>[mailto:pgsql-general-owner@postgresql.org] On Behalf Of Bruno
>Wolff III
>Sent: vrijdag 11 mei 2007 21:18
>To: John Gateley
>Cc: pgsql-general@postgresql.org
>Subject: Re: [GENERAL] Fault Tolerant Postgresql (two
>machines, two postmasters, one disk array)
>
>On Thu, May 10, 2007 at 20:43:20 -0500,
>  John Gateley <gateley@jriver.com> wrote:
>> Sorry if this is a FAQ, I did search and couldn't find much.
>>
>> I need to make my Postgresql installation fault tolerant.
>> I was imagining a RAIDed disk array that is accessible from two (or
>> multiple) computers, with a postmaster running on each computer.
>> (Hardware upgrades could then be done to each computer at different
>> times without losing access to the database).
>>
>> Is this possible?
>
>You can't have two postmasters accessing the same data. Doing
>so will cause corruption. You can have a failover system where
>another postmaster starts after the normal one has stopped.
>But you need to be completely sure the normal postmaster has
>stopped before starting the backup one.

For this you might use heartbeat.
See http://www.linux-ha.org/

They seem to have a good tool to do the job. In general, version 1,
though limited to 2 nodes only is in use for several years and is will
supported with most linux distributions. Also a lot of information is
available on how to set up and getting it to work as desired.
The newer version 2 might provide more features than you actually need.
And since its newer there is fewer use.
I believe heartbeat is also one of the elements in redhats cluster
suite.

- Joris Dobbelsteen