Date: Thu, 27 Apr 2006 12:50:16 -0500
From: "Jim C. Nasby" <jnasby@pervasive.com>
To: Ketema Harris <ketema@gmail.com>, pgsql-performance@postgresql.org
Subject: Re: Running on an NFS Mounted Directory
Message-ID: <20060427175016.GH97354@pervasive.com>
References: <20060427132452.GG31328@mathom.us>
 <C0764241.2CFE%ketema@gmail.com>
	<20060427140417.GH31328@mathom.us>
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On Thu, Apr 27, 2006 at 10:04:19AM -0400, Michael Stone wrote:
> >>redundancy, expandability
> >What I mean by these stupid flavor words is:
> >Redundancy : raid 5.
> 
> You can get that without external storage.
 
Yes, but some dedicated storage devices actually provide good
performance with RAID5. Most simpler solutions give pretty abysmal write
performance.

> >>Do you 
> >>need the ability to do snapshots?
> >Yes.
> 
> If that's a hard requirement you'll have to eat the cost & performance 
> problems of an external solution or choose a platform that will let you 
> do that with direct-attach storage. (Something with a volume manager.)
 
I'm wondering if PITR would suffice. Or maybe even Slony.

> >>Do you want to share one big, expensive, reliable unit between
> >>multiple systems? Will you be doing failover?
> >Yes, and Yes.  Really on one other system, a phone system, but it is the
> >crux of my business and will be writing a lot of recorded phone calls. I am
> >working with a storage company now to set up the failover, I want the db 
> >and
> >phone systems to never no if the storage switched over.
> 
> If you actually have a couple of systems you're trying to fail over, a 
> FC SAN may be a reasonable solution. Depending on your reliability 
> requirement you can have multiple interfaces & FC switches to get 
> redundant paths and a much higher level of storage reliability than you 
> could get with direct attach storage. OTOH, if the DB server itself 
> breaks you're still out of luck. :) You might compare that sort of 
> solution with a solution that has redundant servers and implements the 
> failover in software instead of hardware.

BTW, I know a company here in Austin that does capacity planning for
complex systems like this; contact me off-list if you're interested in
talking to them.
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461