Received: from localhost (unknown [200.46.204.191]) by postgresql.org (Postfix) with ESMTP id 0AE6B2E4686 for ; Wed, 23 Jan 2008 17:06:50 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.191]) (amavisd-maia, port 10024) with ESMTP id 12807-01-3 for ; Wed, 23 Jan 2008 17:06:45 -0400 (AST) Received: from smtp.janestcapital.com (www.janestcapital.com [66.155.124.107]) by postgresql.org (Postfix) with ESMTP id 1E93F2E2D7A for ; Wed, 23 Jan 2008 16:51:11 -0400 (AST) Received: from [172.25.129.161] [38.96.172.125] by janestcapital.com with ESMTP (SMTPD-9.10) id A8BC0174; Wed, 23 Jan 2008 15:51:08 -0500 Message-ID: <4797A8B3.5040605@janestcapital.com> Date: Wed, 23 Jan 2008 15:50:59 -0500 From: Brian Hurt User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Guy Rouillier CC: pgsql-performance@postgresql.org Subject: Re: Making the most of memory? References: <4796BE84.9030803@centriccrm.com> <47979C15.3040406@burntmail.com> In-Reply-To: <47979C15.3040406@burntmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.336 tagged_above=0 required=5 tests=AWL=-0.795, BAYES_50=0.001, DNS_FROM_OPENWHOIS=1.13 X-Spam-Level: X-Archive-Number: 200801/204 X-Sequence-Number: 28443 Guy Rouillier wrote: > Scott Marlowe wrote: > >> I assume you're talking about solid state drives? They have their >> uses, but for most use cases, having plenty of RAM in your server will >> be a better way to spend your money. For certain high throughput, >> relatively small databases (i.e. transactional work) the SSD can be >> quite useful. > > > Unless somebody has changes some physics recently, I'm not > understanding the recent discussions of SSD in the general press. > Flash has a limited number of writes before it becomes unreliable. On > good quality consumer grade, that's about 300,000 writes, while on > industrial grade it's about 10 times that. That's fine for mp3 > players and cameras; even professional photographers probably won't > rewrite the same spot on a flash card that many times in a lifetime. > But for database applications, 300,000 writes is trivial. 3 million > will go a lot longer, but in non-archival applications, I imagine even > that mark won't take but a year or two to surpass. > I think the original poster was talking about drives like these: http://www.texmemsys.com/ Basically, they're not using Flash, they're just big ol' hunks of battery-backed RAM. Not unlike a 10GB battery backed buffer for your raid, except there is no raid. Brian