From owner-freebsd-stable@FreeBSD.ORG Sat Jul 24 11:56:39 2010 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 098B91065674 for ; Sat, 24 Jul 2010 11:56:39 +0000 (UTC) (envelope-from ptyll@nitronet.pl) Received: from mail.nitronet.pl (pop3.nitronet.pl [195.90.106.28]) by mx1.freebsd.org (Postfix) with ESMTP id B84118FC17 for ; Sat, 24 Jul 2010 11:56:38 +0000 (UTC) Received: from mailnull by mail.nitronet.pl with virscan (Exim 4.72 (FreeBSD)) (envelope-from ) id 1OcdLJ-0003kb-1H for freebsd-stable@freebsd.org; Sat, 24 Jul 2010 13:56:37 +0200 Date: Sat, 24 Jul 2010 13:56:30 +0200 From: Pawel Tyll X-Priority: 3 (Normal) Message-ID: <136751861.20100724135630@nitronet.pl> To: freebsd-stable@freebsd.org In-Reply-To: References: <4C47B57F.5020309@langille.org> <4C48E695.6030602@langille.org> <718046944.20100723032259@nitronet.pl> <4C4A42D5.7080805@langille.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable X-Virus-Scanned: Nitronet.pl X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: ptyll@nitronet.pl X-SA-Exim-Scanned: No (on mail.nitronet.pl); SAEximRunCond expanded to false Cc: Adam Vande More Subject: Re: Using GTP and glabel for ZFS arrays X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 24 Jul 2010 11:56:39 -0000 > Easiest way to create sparse eg 20 GB assuming test.img doesn't exist > already No no no. Easiest way to do what you want to do: mdconfig -a -t malloc -s 3t -u 0 mdconfig -a -t malloc -s 3t -u 1 Just make sure to offline and delete mds ASAP, unless you have 6TB of RAM waiting to be filled ;) - note that with RAIDZ2 you have no redundancy with two fake disks gone, and if going with RAIDZ1 this won't work at all. I can't figure out a safe way (data redundancy all the way) of doing things with only 2 free disks and 3.5TB data - third disk would make things easier, fourth would make them trivial; note that temporary disks 3 and 4 don't have to be 2TB, 1.5TB will do. I've done this dozen of times, had no problems, no gray hair, and not a bit of data lost ;)