Thread: 2 servers with 1 database cluster

On Monday 09 Jun 2003 4:49 pm, Mark Cubitt wrote:
> Hi,
>
> we are currently running 2 web/database servers with apache and postgess
> (and php etc), these have differnet sites on them at the moment but we are
> gonna have them load blanced and have both sites on each server.
>
> we will be using storage space with the hosting company to hold the pages
> and the database cluster.
>
> we are planning to have a copy of postgress running on both servers
> accessing the cluster on the storage space at the same time, is this
> possiable and if so is there any possiable problems.

If you mean two postmasters accessing a shared disk - no this is not possible
- your data will be corrupted.
I recall a long discussion on this some months ago, you might like to look at
the archives.

> and how would the database cluster handle 2 accesses to the same record at
> once?

Badly.

You want one of two things:
1. One shared PG installation behind your two webservers
2. Two individual PG installations replicating between each other.

--
  Richard Huxton

As another poster already pointed out, running two postmasters against the
same storage is officially a Very Bad Idea.

Also, it sounded like you might be looking at network attached storage
etc. to put your database on.  While isn't a Very Bad Idea, it is a path
fraught with danger.  For a database server, you're probably better off
having one very fast box that's either replicated or simply hot backed up
nightly from the live box.  Any dual CPU machine with a gig of memory and
a stack of drives underneath it can handle two front end application
servers handily.