Re: postgresql cluster on SAN

> Hi,
>
> Can i create create a cluster of postgresql server by sharing
> the database file on a SAN? I am also looking into slony but
> slony replicate data to each server and my database will
> potentially have terabytes of data. I am thinking about a
> solution where a cluster of database server will share
> database files on SAN, can this be done? I am also looking
> for a load balancing salution for the postgresql database.
> Any sugestion?
>

Yes, you can, but *only* if you use some HA clustering software that
makes sure that *only one node at a time accesses the disk resources*.
This means that one node will be completely passive (postmaster not even
started! filesystem not even mounted!) and will only be activated on
failover (at which time the HA software must *ensure* that the old
postmaster can no longer access the disk resources).
(Don't know what they are called on linux, I'm sure they exist, as well
as for any commercial Unix. It should work fine with MSCS if you're on
win32)

This will give you failover, but *not* load balancing. For load
balancing you need to replicate the data in some way (slony being one of
the options, but there are others). Once you've done this, you can front
the system with pgpool for load balancing.

//Magnus