Re: RAID card recommendation

Matthew Wakeling wrote:
> People have mentioned Areca as making good RAID controllers. We're
> looking at the "Areca ARC-1220 PCI-Express x8 SATA II" as a
> possibility. Does anyone have an opinion on whether it is a turkey or
> a star?
Performance should be OK but not great compared with some of the newer
alternatives (this design is a few years old now). The main issue I've
had with this series of cards is that the command-line tools are very
hit or miss. See
http://notemagnet.blogspot.com/2008/08/linux-disk-failures-areca-is-not-so.html
for a long commentary about the things I was disappointed by on the
similar ARC-1210 once I actually ran into a drive failure on one. As
Scott points out there, they have other cards with a built-in management
NIC that allows an alternate management path, and I believe those have
better performance too.

> Another possibility is a 3-ware card of some description.
I've put a fair number of 9690SA cards in systems with little to
complain about. Performance was reasonable as long as you make sure to
tweak the read-ahead: http://www.3ware.com/kb/article.aspx?id=11050
Ignore most of the rest of their advice on that page though--for
example, increasing vm.dirty_background_ratio and vm.dirty_ratio is an
awful idea for PostgreSQL use, where if anything you want to decrease
the defaults.

Also, while they claim you can connect SAS drives to these cards, they
don't support sending SMART commands to them and support seemed pretty
limited overall for them. Stick with plain on SATA ones.

--
Greg Smith 2ndQuadrant Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.com