From owner-freebsd-fs@FreeBSD.ORG Fri May 22 21:15:05 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 07BD7106566C for ; Fri, 22 May 2009 21:15:05 +0000 (UTC) (envelope-from brooks@lor.one-eyed-alien.net) Received: from lor.one-eyed-alien.net (cl-162.ewr-01.us.sixxs.net [IPv6:2001:4830:1200:a1::2]) by mx1.freebsd.org (Postfix) with ESMTP id 688C58FC1E for ; Fri, 22 May 2009 21:15:04 +0000 (UTC) (envelope-from brooks@lor.one-eyed-alien.net) Received: from lor.one-eyed-alien.net (localhost [127.0.0.1]) by lor.one-eyed-alien.net (8.14.3/8.14.3) with ESMTP id n4MLFDrg002557; Fri, 22 May 2009 16:15:13 -0500 (CDT) (envelope-from brooks@lor.one-eyed-alien.net) Received: (from brooks@localhost) by lor.one-eyed-alien.net (8.14.3/8.14.3/Submit) id n4MLFDw7002556; Fri, 22 May 2009 16:15:13 -0500 (CDT) (envelope-from brooks) Date: Fri, 22 May 2009 16:15:13 -0500 From: Brooks Davis To: Randy Bush Message-ID: <20090522211513.GB2160@lor.one-eyed-alien.net> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="tsOsTdHNUZQcU9Ye" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-3.0 (lor.one-eyed-alien.net [127.0.0.1]); Fri, 22 May 2009 16:15:14 -0500 (CDT) Cc: freebsd-fs Subject: Re: raidz2 a bit big 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: Fri, 22 May 2009 21:15:05 -0000 --tsOsTdHNUZQcU9Ye Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, May 22, 2009 at 02:05:39PM -0700, Randy Bush wrote: > a dozen 2tb drives in a raidz2 >=20 > dfw1.psg.com:/root# zpool status > pool: tank > state: ONLINE > scrub: none requested > config: >=20 > NAME STATE READ WRITE CKSUM > tank ONLINE 0 0 0 > raidz2 ONLINE 0 0 0 > da0s3 ONLINE 0 0 0 > da1s3 ONLINE 0 0 0 > da2s1 ONLINE 0 0 0 > da3s1 ONLINE 0 0 0 > da4s1 ONLINE 0 0 0 > da5s1 ONLINE 0 0 0 > da6s1 ONLINE 0 0 0 > da7s1 ONLINE 0 0 0 > da8s1 ONLINE 0 0 0 > da9s1 ONLINE 0 0 0 > da10s1 ONLINE 0 0 0 > da11s1 ONLINE 0 0 0 >=20 > errors: No known data errors >=20 > i expected to get 10T effective because of the raidz2, but got 20T > ^ > dfw1.psg.com:/root# df -H > Filesystem Size Used Avail Capacity Mounted on > /dev/da0s1a 17G 3.8G 12G 25% / > devfs 1.0k 1.0k 0B 100% /dev > /dev/md0 130M 90k 119M 0% /tmp > tank 19T 0B 19T 0% /tank > tank/usr 19T 0B 19T 0% /tank/usr > tank/usr/home 19T 0B 19T 0% /tank/usr/home > tank/var 19T 0B 19T 0% /tank/var > tank/var/spool 19T 0B 19T 0% /tank/var/spool > tank/data 19T 0B 19T 0% /tank/data >=20 > clue bat? raidz2 is RAID6ish in that two disks of a raid group go to parity to allow you to survive double faults. Thus your expected size is: (12-2)*2TB =3D 20TB. -- Brooks --tsOsTdHNUZQcU9Ye Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iD8DBQFKFxXgXY6L6fI4GtQRAuJiAKCeRp31X+4k+uttIL2T8Z+EIcpn7QCdGCPi NDyhemHtfwYHfASZ2d/Iw7s= =PUtN -----END PGP SIGNATURE----- --tsOsTdHNUZQcU9Ye--