Re: postgres in HA constellation

On Wed, Oct 04, 2006 at 11:23:45 -0000,
Sebastian Reitenbach <itlistuser(at)rapideye(dot)de> wrote:
>
> something I thought that might work:
> is there sth. that will repair an inconsisten postgresql datastore? e.g. the
> master database died, the slave will mount the storage, then repair it in a
> reasonable time, and then start to work.

You can just start the slave server and it will recover using th WAL files
and should do so in a short time. However, you MUST be certain that the
master is no longer running when the slave starts or your database WILL BE
TRASHED.
>
> are there any other possibilities that might work that I am not aware of?
> anybody has experiences with postgres in a HA environment with shared storage?

You can also use servers with redundant hardware (hotplug CPUs and the like)
to make failure less likely. If you get the hardware failure rates down to
that of your storage system, that might be good enough for your purposes.

If you have multiple data centers to protect against disaster, then you might
look at SLONY which you can use to replicate to a slave system. However, I
think it is possible for the master to report a transaction as commited
before it is shipped off to the slave, so that if the master fails you might
lose some transactions when switching to the slave. But double check with
the SLONY documentation on this.