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Re: Making the most of memory?

From: Florian Weimer <fweimer(at)bfk(dot)de>
To: Chris Browne <cbbrowne(at)acm(dot)org>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Making the most of memory?
Date: 2008-01-25 08:18:41
Message-ID: 824pd28gim.fsf@mid.bfk.de (view raw or flat)
Thread:
Lists: pgsql-performance
* Chris Browne:

>> A dedicated RAID controller with battery-backed cache of ssuficient
>> size and two mirrored disks should not perform that bad, and has the
>> advantage of easy availability.
>
> That won't provide as "souped up" performance as "WAL on SSD," and
> it's from technical people wishing for things that some of those
> things actually emerge...

For WAL (I/O which is mostly sequential), the proposed approach isn't
that bad.  You can easily get more than 15,000 write transactions per
second, with a single thread.  Good luck finding a SSD NAS with a
60 usec round-trip time. 8->

Something which directly speaks SATA or PCI might offer comparable
performance, but SSD alone isn't sufficient.

-- 
Florian Weimer                <fweimer(at)bfk(dot)de>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstra├če 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99

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