Re: Which RAID Controllers to pick/avoid?

From: Greg Smith <greg(at)2ndquadrant(dot)com>
To: Dan Birken <birken(at)gmail(dot)com>
Cc: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Which RAID Controllers to pick/avoid?
Date: 2011-02-03 15:02:21
Message-ID: 4D4AC37D.2070207@2ndquadrant.com
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Dan Birken wrote:
> - Is the supercap + flash memory considered superior to the BBU in
> practice? Is that type of system well tested?

The main risk is that it's a pretty new approach. The standard BBU
setup has been used for a long time now; this whole flash+supercap thing
has only showed up in the last couple of years. Theoretically it's
better; the #1 weakness of the old battery setup was only surviving an
outage of a few days, and storing to flash doesn't have that issue.
It's just got the usual risks of something new.

> - Is the linux support of the LSI and Adaptec cards comparable?

Seems to be. The latest versions of Adaptec's arcconf utility even
provide about the same quality of command-line tools as LSI's megactl,
after being behind in that area for a while. Only quirk, and I can't
say where this was the manufacturer of the box or not because they
installed the base OS, is that the 5405 setup I saw didn't turn off the
write caches on the individual drives of the system. That's the
standard safe practice and default for the LSI cards.

--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books

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