In any of these situations your external RAID array must have two channels.
1) in a fail-over situation your postgresql daemon must be started after the
other box fails. When it starts it will read the current state of the
filesystem
and may be able to read the tables as they were when the last write occurred
on
the first box.
2) in an High Availability (HA) situation you need some sort of database
broker
that keeps both database daemons happy. Something like Oracle's Parallel
server
option. This also involves row-level locking of records.
HA or Fail-over are very expensive solutions (hardware and software required)
and therefore you need to question whether you really want to do this.
On Tue, 17 Oct 2000 16:51:35 -0400, "Clark, Joel" <jclark@lendingtree.com>
wrote:
> As long as the requirement is only fail-over and not load-balancing, it
> *might* be doable...but running against tables mounted across NFS will still
> be slow, relatively speaking...
>
> jc
>
> -----Original Message-----
> From: Adam Lang [mailto:aalang@rutgersinsurance.com]
> Sent: Tuesday, October 17, 2000 3:54 PM
> To: pgsql-interfaces@postgreSQL.org
> Subject: Re: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> possible?]
>
>
> Granted it probably not the most efficient solution, but if it is something
> that is really a problem... what about having your dual server, one data
> source setup, but the second server is idle and does nothing and only kicks
> in if the primary drops? Might be more complicated to setup than it sounds
> and there still would be a time delay for the second to pick up, but it
> technically would eliminate the two servers butting heads. Again though,
> not very efficient solution... unless it is very critical and money is no
> object. :)
>
> Adam Lang
> Systems Engineer
> Rutgers Casualty Insurance Company
> ----- Original Message -----
> From: "Joseph Shraibman" <jks@selectacast.net>
> To: <pgsql-interfaces@postgreSQL.org>
> Sent: Tuesday, October 17, 2000 2:53 PM
> Subject: [Fwd: [INTERFACES] 2 computers 1hd 2 postgres daemons. Is it
> possible?]
>
>
> >
> > --
> > Joseph Shraibman
> > jks@selectacast.net
> > Increase signal to noise ratio. http://www.targabot.com
>