X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id C50BC9DD761 for ; Fri, 9 Dec 2005 11:57:26 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 16126-02 for ; Fri, 9 Dec 2005 11:57:31 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from frank.wiles.org (frank.wiles.org [24.124.39.75]) by postgresql.org (Postfix) with ESMTP id 6B8F29DD732 for ; Fri, 9 Dec 2005 11:57:24 -0400 (AST) Received: from kungfu (frank.wiles.org [127.0.0.1]) by frank.wiles.org (8.13.1/8.13.1) with SMTP id jB9FvQBD004363; Fri, 9 Dec 2005 09:57:27 -0600 Date: Fri, 9 Dec 2005 09:58:36 -0600 From: Frank Wiles To: "Jeremy Haile" Cc: pgsql-performance@postgresql.org Subject: Re: opinion on disk speed Message-Id: <20051209095836.1c846c2e.frank@wiles.org> In-Reply-To: <1134137725.8767.249418727@webmail.messagingengine.com> References: <1134137725.8767.249418727@webmail.messagingengine.com> X-Mailer: Sylpheed version 2.0.1 (GTK+ 2.6.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0 required=5 tests=[none] X-Spam-Score: 0 X-Spam-Level: X-Archive-Number: 200512/264 X-Sequence-Number: 16085 On Fri, 09 Dec 2005 09:15:25 -0500 "Jeremy Haile" wrote: > > one other note, you probably don't want to use all the disks in a > > raid10 array, you probably want to split a pair of them off into a > > seperate raid1 array and put your WAL on it. > > Is a RAID 1 array of two disks sufficient for WAL? What's a typical > setup for a high performance PostgreSQL installation? RAID 1 for WAL > and RAID 10 for data? > > I've read that splitting the WAL and data offers huge performance > benefits. How much additional benefit is gained by moving indexes to > another RAID array? Would you typically set the indexes RAID array up > as RAID 1 or 10? Yes most people put the WAL on a RAID 1 and use all the remaining disks in RAID 10 for data. Whether or not moving your indexes onto a different RAID array is worthwhile is harder to judge. If your indexes are small enough that they will usually be in ram, but your data is to large to fit then having the extra spindles available on the data partition is probably better. As always, it is probably best to test both configurations to see which is optimal for your particular application and setup. --------------------------------- Frank Wiles http://www.wiles.org ---------------------------------