From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1G86nU-0003sX-Mh for qemu-devel@nongnu.org; Tue, 01 Aug 2006 22:49:24 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1G86nT-0003s1-Aw for qemu-devel@nongnu.org; Tue, 01 Aug 2006 22:49:24 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1G86nT-0003ry-4z for qemu-devel@nongnu.org; Tue, 01 Aug 2006 22:49:23 -0400 Received: from [64.233.182.191] (helo=nf-out-0910.google.com) by monty-python.gnu.org with esmtp (Exim 4.52) id 1G86qU-0004AK-2i for qemu-devel@nongnu.org; Tue, 01 Aug 2006 22:52:30 -0400 Received: by nf-out-0910.google.com with SMTP id m19so501382nfc for ; Tue, 01 Aug 2006 19:49:21 -0700 (PDT) Message-ID: Date: Wed, 2 Aug 2006 04:49:21 +0200 From: "andrzej zaborowski" Sender: balrogg@gmail.com Subject: Re: [Qemu-devel] Wipe patch In-Reply-To: <44D00D26.2050201@wasp.net.au> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <44D00D26.2050201@wasp.net.au> Reply-To: balrogg@gmail.com, qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On 02/08/06, Brad Campbell wrote: > ZIGLIO, Frediano, VF-IT wrote: > > Hi, > > well, this is not a definitive patch but it works. The aim is to be > > able to wipe the disk without allocating entire space. When you wipe a > > disk the program fill disk with zero bytes so disk image increase to > > allocate all space. This just patch detect null byte writes and do not > > write all zero byte clusters. > > > > I've been giving this some pretty heavy testing over the last week and can say I've not noticed any > negative performance impact or any other adverse side effects, not to mention the speedup when doing > re-packing (which I do fairly regularly on both ext3 and ntfs guest filesystems). > > While I'm here does anyone know of a simple program, either dos or linux based for wiping unused > space on fat filesystems? The only ones I've found so far have been windows based. I don't know if you mean just zeroing unused parts or reordering the data and stuff like defragmentation. If you mean the former, there's a universal method: dd if=/dev/zero of=xxx; rm xxx where xxx is a path to a new file on the filesystem, which must be mounted. It will creata a zero filled file there, which will fill all availiable space, and remove the file afterwards. I used this when I needed to send filesystem images through internet so that they compressed well. If you add dd= it might take less time to write the file. > > This patch now conflicts pretty heavily with the new AIO changes it would seem. Further > investigation required. > > Ta, > Brad > -- > "Human beings, who are almost unique in having the ability > to learn from the experience of others, are also remarkable > for their apparent disinclination to do so." -- Douglas Adams > > > _______________________________________________ > Qemu-devel mailing list > Qemu-devel@nongnu.org > http://lists.nongnu.org/mailman/listinfo/qemu-devel > Regards, -- balrog 2oo6 Dear Outlook users: Please remove me from your address books http://www.newsforge.com/article.pl?sid=03/08/21/143258