From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1G8779-0003pX-1a for qemu-devel@nongnu.org; Tue, 01 Aug 2006 23:09:43 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1G8777-0003oI-7r for qemu-devel@nongnu.org; Tue, 01 Aug 2006 23:09:42 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1G8777-0003oF-2u for qemu-devel@nongnu.org; Tue, 01 Aug 2006 23:09:41 -0400 Received: from [203.190.192.17] (helo=wasp.net.au) by monty-python.gnu.org with esmtp (Exim 4.52) id 1G87A8-0005uM-79 for qemu-devel@nongnu.org; Tue, 01 Aug 2006 23:12:48 -0400 Message-ID: <44D01770.3040702@wasp.net.au> Date: Wed, 02 Aug 2006 07:09:36 +0400 From: Brad Campbell MIME-Version: 1.0 Subject: Re: [Qemu-devel] Wipe patch References: <44D00D26.2050201@wasp.net.au> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Reply-To: 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 andrzej zaborowski wrote: >> 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. > Oops, I mean "bs=" ofcourse. Yep, been doing similar, but the neato wipe programs generally also do cluster tails and unused directory entries and allow a really great compression ratio. Ta for the advice though. 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