From owner-freebsd-fs@FreeBSD.ORG Mon Nov 30 22:40:40 2009 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C42301065694 for ; Mon, 30 Nov 2009 22:40:40 +0000 (UTC) (envelope-from andrew@modulus.org) Received: from email.octopus.com.au (email.octopus.com.au [122.100.2.232]) by mx1.freebsd.org (Postfix) with ESMTP id D54B98FC1D for ; Mon, 30 Nov 2009 22:40:39 +0000 (UTC) Received: by email.octopus.com.au (Postfix, from userid 1002) id 8D4355CB94D; Tue, 1 Dec 2009 09:17:58 +1100 (EST) X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on email.octopus.com.au X-Spam-Level: X-Spam-Status: No, score=-1.4 required=10.0 tests=ALL_TRUSTED autolearn=failed version=3.2.3 Received: from [220.233.52.14] (14.52.233.220.static.exetel.com.au [220.233.52.14]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: admin@email.octopus.com.au) by email.octopus.com.au (Postfix) with ESMTP id 273385CB8BB; Tue, 1 Dec 2009 09:17:54 +1100 (EST) Message-ID: <4B14495E.7050306@modulus.org> Date: Tue, 01 Dec 2009 09:38:22 +1100 From: Andrew Snow User-Agent: Thunderbird 2.0.0.6 (X11/20070926) MIME-Version: 1.0 To: Zaphod Beeblebrox , freebsd-fs@freebsd.org References: <2ae8edf30911300120x627e42a9ha2cf003e847d4fbd@mail.gmail.com> <4B139AEB.8060900@jrv.org> <2ae8edf30911300425g4026909bm9262f6abcf82ddcd@mail.gmail.com> <5f67a8c40911301233s46a2818at9051c4ebbacf7e25@mail.gmail.com> In-Reply-To: <5f67a8c40911301233s46a2818at9051c4ebbacf7e25@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Subject: Re: ZFS guidelines - preparing for future storage expansion X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Nov 2009 22:40:40 -0000 Zaphod Beeblebrox wrote: > I moved from 5x 750G to 5x 1.5T disks this way earlier this year. It takes > a _long_ time. resilvering 750g (they were about 98% full when I did this) > onto the 1.5T disks took about 12 hours each. Currently there is no "read-ahead" for scrubbing and resilvering, so it only talks to one disk and at a time and proceeds using only about half the I/O capacity of your disks (or less). Read-ahead is one of the planned features for ZFS next year. Also, when your disks are 98% or more full and you are doing any writes at all ZFS spends a long time looking for free blocks with an inefficient algorithm. An improved "disk full" algorithm is also planned for next year. - Andrew