From owner-freebsd-questions@FreeBSD.ORG Wed Mar 24 21:23:56 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CE626106566C for ; Wed, 24 Mar 2010 21:23:56 +0000 (UTC) (envelope-from kraduk@googlemail.com) Received: from fg-out-1718.google.com (fg-out-1718.google.com [72.14.220.155]) by mx1.freebsd.org (Postfix) with ESMTP id 55A928FC0C for ; Wed, 24 Mar 2010 21:23:55 +0000 (UTC) Received: by fg-out-1718.google.com with SMTP id l26so1169128fgb.13 for ; Wed, 24 Mar 2010 14:23:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:cc:content-type; bh=1jUljovol7I5ynDm0YLMgEQo2Vk2lh/rL6XCc1P43X0=; b=AYQQCDZnmtw2usE917sGYzkDVHJhJ7nQJuQss48xxsL3PDq5NhaOkQNCspDwDxzclq SC7OavcjCPycpLseXY0swCt3/c+dcNlpRLka8qbmrbQYO4Q8iUJ0xg2PBqaaL3I8sAUS ab6/8jrvn9xwaZgI6mipkRQzrIdvLdBbOx08g= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=ajiScg2uJ9p2sm4bVKPh064Euxqw5vyV7eSad4VXKu8+DrrlkifaYcT+boLmzF8ys0 LOECAoYconfr5mr9jfWbORZrOE051uqZq2kYh4PFm2A9IgTJxsaYgL8xZa2Leei4Li+C AhHaJeFHIHIMdQZh7bK+/a8gnPAxqhK91pesw= MIME-Version: 1.0 Received: by 10.239.183.146 with SMTP id u18mr1037680hbg.174.1269465834203; Wed, 24 Mar 2010 14:23:54 -0700 (PDT) In-Reply-To: <4BA9F87E.7050205@infracaninophile.co.uk> References: <20100324103151.GA2598@potato> <4BA9F87E.7050205@infracaninophile.co.uk> Date: Wed, 24 Mar 2010 21:23:54 +0000 Message-ID: From: krad To: Matthew Seaman Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: John , freebsd-questions@freebsd.org Subject: Re: simple zfs query X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Mar 2010 21:23:56 -0000 On 24 March 2010 11:33, Matthew Seaman wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 24/03/2010 10:31:51, John wrote: > > With ZFS and 3x 2Tb SATA disks, what percentage of theoretical diskspace > > would I realise? I'm hoping at least 5Tb would be usable? > > That depends on how you configure your zpool. The choices are: > > disk -- just uses the disk directly as a vdev. Means you can use 100% > of the space, but you have absolutely no resilience > > mirror -- for which you'ld need an even number of disks and you get 50% > of the raw as usable space. Can survive at least one disk > failure, and possibly up to as many as half of the disks > failing. > > raidz -- single parity (equivalent to RAID5). For N disks, 1 disk > worth is used for parity data, leaving N - 1 disks' worth as > the actual capacity. So you'ld get 66% of raw in your case. > Can survive failure of any one disk. > > raidz2 -- double parity (equivalent to RAID6). For N disks, 2 disks > worth are used for parity data, leaving N - 2 disks worth as > actual capacity. Or 33% of raw in your case. Can survive > failure of any two disks. > > Note that 3 drives is the minimum for either of the raidz types, and > won't give you the best performance. See zpool(1M) for details. > > Cheers, > > Matthew > > - -- > Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard > Flat 3 > PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate > Kent, CT11 9PW > -----BEGIN PGP SIGNATURE----- > Version: GnuPG/MacGPG2 v2.0.14 (Darwin) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iEYEARECAAYFAkup+H4ACgkQ8Mjk52CukIx8HQCfcGTI3wh3QsxNmDS1nPkbw8WU > cWIAoJO8rys1R7SfasVkse2htfqOqVrF > =AWpE > -----END PGP SIGNATURE----- > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to " > freebsd-questions-unsubscribe@freebsd.org" > If you want 100% of the drives you could have a pool per drive. Its not as nice as one big pool, but its less risky than one big raid0