From owner-freebsd-fs@FreeBSD.ORG Tue Jun 14 15:27:13 2011 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 0A9601065670 for ; Tue, 14 Jun 2011 15:27:13 +0000 (UTC) (envelope-from daniel@digsys.bg) Received: from smtp-sofia.digsys.bg (smtp-sofia.digsys.bg [193.68.3.230]) by mx1.freebsd.org (Postfix) with ESMTP id 8A8C08FC29 for ; Tue, 14 Jun 2011 15:27:12 +0000 (UTC) Received: from dcave.digsys.bg (dcave.digsys.bg [192.92.129.5]) (authenticated bits=0) by smtp-sofia.digsys.bg (8.14.4/8.14.4) with ESMTP id p5EFR1eA056909 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO) for ; Tue, 14 Jun 2011 18:27:07 +0300 (EEST) (envelope-from daniel@digsys.bg) Message-ID: <4DF77DC5.7030503@digsys.bg> Date: Tue, 14 Jun 2011 18:27:01 +0300 From: Daniel Kalchev User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.17) Gecko/20110519 Thunderbird/3.1.10 MIME-Version: 1.0 To: freebsd-fs@freebsd.org References: <9544F7B9-E286-4266-86E3-B4D1A667CBBD@itassistans.se> <20110614150613.GB27199@DataIX.net> <61335943-0172-4483-A221-5C77CD8BAEFB@itassistans.se> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: Disk usage and ZFS deduplication 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: Tue, 14 Jun 2011 15:27:13 -0000 On 14.06.11 18:17, Per von Zweigbergk wrote: > > But in this case it's not the entire file being hardlinked, rather just some parts of the file being deduplicated so it's not exactly the same. Or is it? This is why I asked on the mailing list. :-) > > Consider, 'storage' is different than file allocation. With ZFS dedup, the storage (layer) decides whether to store new record, or to link it to an existing record. You have no control over this. If you ask how many blocks the file occupies in storage, that would be the entire file size. If some of the blocks are shared with other files (or whatever) that does not change how many blocks the file uses. It is different with compression. Daniel