Received: from localhost (maia-4.hub.org [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 9B9859FB764 for ; Wed, 9 May 2007 00:51:53 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 51433-03 for ; Wed, 9 May 2007 00:51:50 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from westnet.com (westnet.com [216.187.52.2]) by postgresql.org (Postfix) with ESMTP id 8DE6E9FB763 for ; Wed, 9 May 2007 00:51:50 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id l493pp58005768 for ; Tue, 8 May 2007 23:51:51 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id l493ppE8005765 for ; Tue, 8 May 2007 23:51:51 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Tue, 8 May 2007 23:51:51 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: pgsql-performance@postgresql.org Subject: Re: Best OS for Postgres 8.2 In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200705/170 X-Sequence-Number: 24560 On Tue, 8 May 2007, Luke Lonergan wrote: > From discussions with the developers, the biggest issue is a technical > one: the Linux VFS layer makes the [ZFS] port difficult. Difficult on two levels. First you'd have to figure out how to make it work at all; then you'd have to reshape it into a form that it would be acceptable to the Linux kernel developers, who haven't seemed real keen on the idea so far. The standard article I'm you've already seen this week on this topic is Jeff Bonwick's at http://blogs.sun.com/bonwick/entry/rampant_layering_violation What really bugged me was his earlier article linked to there where he talks about how ZFS eliminates the need for hardware RAID controllers: http://blogs.sun.com/bonwick/entry/raid_z While there may be merit to that idea for some applications, like situations where you have a pig of a RAID5 volume, that's just hype for database writes. "We issue the SYNCHRONIZE CACHE command to the disks after pushing all data in a transaction group"--see, that would be the part the hardware controller is needed to accelerate. If you really care about whether your data hit disk, there is no way to break the RPM barrier without hardware support. The fact that he misunderstands such a fundamental point makes me wonder what other gigantic mistakes might be buried in his analysis. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD