From owner-freebsd-fs@FreeBSD.ORG Sun Jul 14 08:50:20 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 958D76E3 for ; Sun, 14 Jul 2013 08:50:20 +0000 (UTC) (envelope-from nowakpl@platinum.linux.pl) Received: from platinum.linux.pl (platinum.edu.pl [81.161.192.4]) by mx1.freebsd.org (Postfix) with ESMTP id 5B2799BF for ; Sun, 14 Jul 2013 08:50:18 +0000 (UTC) Received: by platinum.linux.pl (Postfix, from userid 87) id 41DEA2BC19D; Sun, 14 Jul 2013 10:50:11 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on platinum.linux.pl X-Spam-Level: X-Spam-Status: No, score=-1.3 required=3.0 tests=ALL_TRUSTED,AWL autolearn=disabled version=3.3.2 Received: from [10.255.0.2] (unknown [83.151.38.73]) by platinum.linux.pl (Postfix) with ESMTPA id 0F1802BC196 for ; Sun, 14 Jul 2013 10:50:11 +0200 (CEST) Message-ID: <51E26632.8030907@platinum.linux.pl> Date: Sun, 14 Jul 2013 10:49:54 +0200 From: Adam Nowacki User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 To: freebsd-fs@freebsd.org Subject: Re: Efficiency of ZFS ZVOLs. References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 14 Jul 2013 08:50:20 -0000 On 2013-07-14 09:55, Zaphod Beeblebrox wrote: > [1:3:303]root@virtual:~> zfs list -rt all vr2/Steam > NAME USED AVAIL REFER MOUNTPOINT > vr2/Steam 3.25T 9.27T 1.18T - > vr2/Steam@20130528-0029 255M - 1.18T - > vr2/Steam@20130529-0221 172M - 1.18T - > > vr2/Steam is a ZVOL exported by iSCSI to my desktop and it contains an NTFS > filesystem which is mounted into C:\Program Files (x86)\Steam. Windows > sees this drive as a 1.99T drive of which 1.02T is used. > > Now... the value of "REFER" seems quite right: 1.18T vs. 1.02T is pretty > good... but the value of "USED" seems _way_ out. 3.25T ... even regarding > that more of the disk might have been "touched" (ie: used from the ZVOL's > impression) than is used, it seems too large. Neither is it 1.18T + 255M + > 172M. This is how much space would be required to store the snapshots plus 2TB volume with no shared blocks between any of the snapshots. 1.18T from snapshots + 2T reservation = 3.18T, just about the 3.25T displayed. You can remove the reservation with 'zfs set refreservation=none vr2/Steam'.