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Re: How to improve db performance with $7K?

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: Bjoern Metzdorf <bm(at)turtle-entertainment(dot)de>
Cc: Steve Poe <spoe(at)sfnet(dot)cc>,performance pgsql <pgsql-performance(at)postgresql(dot)org>
Subject: Re: How to improve db performance with $7K?
Date: 2005-03-26 20:55:58
Message-ID: 200503261255.59007.josh@agliodbs.com (view raw or flat)
Thread:
Lists: pgsql-performance
Bjoern, Josh, Steve,

> Get 12 or 16 x 74GB Western Digital Raptor S-ATA drives, one 3ware
> 9500S-12 or two 3ware 9500S-8 raid controllers with a battery backup
> unit (in case of power loss the controller saves unflushed data), a
> decent tyan board for the existing dual xeon with 2 pci-x slots and a
> matching 3U case for 12 drives (12 drives internal).

Based on both my testing and feedback from one of the WD Raptor engineers, 
Raptors are still only optimal for 90% read applications.  This makes them a 
great buy for web applications (which are 95% read usually) but a bad choice 
for OLTP applicaitons which sounds more like what Steve's describing.  For 
those, it would be better to get 6 quality SCSI drives than 12 Raptors.

The reason for this is that SATA still doesn't do bi-directional traffic very 
well (simultaneous read and write) and OSes and controllers simply haven't 
caught up with the drive spec and features.  WD hopes that in a year they 
will be able to offer a Raptor that performs all operations as well as a 10K 
SCSI drive, for 25% less ... but that's in the next generation of drives, 
controllers and drivers.

Steve, can we clarify that you are not currently having any performance 
issues, you're just worried about failure?   Recommendations should be based 
on whether improving applicaiton speed is a requirement ...

> Here in Germany chassis by Chenbro are quite popular, a matching one for
> your needs would be the chenbro RM312 or RM414
> (http://61.30.15.60/product/product_preview.php?pid=90 and
> http://61.30.15.60/product/product_preview.php?pid=95 respectively).

The Chenbros are nice, but kinda pricey ($800) if Steve doesn't need the 
machine to be rackable.

If your primary goal is redundancy, you may wish to consider the possibility 
of building a brand-new machine for $7k (you can do a lot of machine for 
$7000 if it doesn't have to be rackable) and re-configuring the old machine 
and using it as a replication or PITR backup.   This would allow you to 
configure the new machine with only a moderate amount of hardware redundancy 
while still having 100% confidence in staying running.

-- 
Josh Berkus
Aglio Database Solutions
San Francisco

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