From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LB81p-0007Rz-GH for qemu-devel@nongnu.org; Fri, 12 Dec 2008 08:26:01 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LB81o-0007RM-0I for qemu-devel@nongnu.org; Fri, 12 Dec 2008 08:26:01 -0500 Received: from [199.232.76.173] (port=53224 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LB81n-0007RC-Q4 for qemu-devel@nongnu.org; Fri, 12 Dec 2008 08:25:59 -0500 Received: from main.gmane.org ([80.91.229.2]:32859 helo=ciao.gmane.org) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LB81n-0001l7-Gl for qemu-devel@nongnu.org; Fri, 12 Dec 2008 08:25:59 -0500 Received: from list by ciao.gmane.org with local (Exim 4.43) id 1LB81j-0005Is-PV for qemu-devel@nongnu.org; Fri, 12 Dec 2008 13:25:55 +0000 Received: from adsl-69-234-198-192.dsl.irvnca.pacbell.net ([69.234.198.192]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 12 Dec 2008 13:25:55 +0000 Received: from w41ter by adsl-69-234-198-192.dsl.irvnca.pacbell.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 12 Dec 2008 13:25:55 +0000 From: walt Date: Fri, 12 Dec 2008 05:25:44 -0800 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit In-Reply-To: Sender: news Subject: [Qemu-devel] Re: snapshot vs COW? 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 Jun Koi wrote: > Hi, > > From what I see, both snapshot and COW features can be used to try > some changes on the file image before we the change back to the > original image. > > But what is the advantages of snapshot over COW, and in which case we > should use snapshot, but not COW? Vice verse, when COW is more > appropriate? > > Many thanks, > Jun COW is a nice feature but it is currently broken, so don't use it until it gets fixed. When you commit any changes your backing file will be corrupted.