Re: [sfpug] DATA directory on network attached storage

On Fri, Apr 08, 2005 at 10:01:55AM -0700, Jeff Frost wrote:
> We are currently considering the possibility of creating a warm standby
> machine utilizing heartbeat and a network attached storage device for the
> DATA directory.  The idea being that the warm standby machine has its
> postmaster stopped.  When heartbeat detects the death of the master server,
> the postmaster is started up on the warm standby using the shared DATA
> directory. Other than the obvious problems of both postmasters
> inadvertently attempting access at the same time, I'm curious to know if
> anyone has tried any similar setups and what the experiences have been.
> Specifically is the performance of gigE good enough to allow postgres to
> perform under load with an NFS mounted DATA dir?  Are there other problems
> I haven't thought about?  Any input would be greatly appreciated.

We (Zapatec Inc) have been running lots of Pg dbs off of a Network Appliance
fileserver (NFS TCPv3) with FreeBSD client machines for several years now with
no problems AFAICT other than insufficient bandwidth between servers and the
fileserver (for one application, www.fastbuzz.com, 100baseTX (over a private
switched network) was insufficient, but IDE-UDMA was fine, so GigE would have
worked too, but we couldn't justify purchasing a new GigE adapter for our
Netapp).

We have the same setup as you would like, allowing for warm standby(s),
however we haven't had to use them at all.

We have not, AFAICT, had any problems with the traffic over NFS as far as
reliability -- I'm sure there is a performance penalty, but the reliability
and scalability gains more than offset that.

FWIW, if I were to do this anew, I would probably opt for iSCSI over GigE with
a NetApp.

Adi