From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1K4I2O-0005N2-My for qemu-devel@nongnu.org; Thu, 05 Jun 2008 12:10:04 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1K4I2O-0005Mc-0F for qemu-devel@nongnu.org; Thu, 05 Jun 2008 12:10:04 -0400 Received: from [199.232.76.173] (port=36257 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1K4I2N-0005MV-Sl for qemu-devel@nongnu.org; Thu, 05 Jun 2008 12:10:03 -0400 Received: from mx20.gnu.org ([199.232.41.8]:4439) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1K4HMm-0000aH-CB for qemu-devel@nongnu.org; Thu, 05 Jun 2008 11:27:04 -0400 Received: from mail2.shareable.org ([80.68.89.115]) by mx20.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1K4EOs-0007ZH-An for qemu-devel@nongnu.org; Thu, 05 Jun 2008 08:17:02 -0400 Received: from jamie by mail2.shareable.org with local (Exim 4.63) (envelope-from ) id 1K4EOk-0005zr-RD for qemu-devel@nongnu.org; Thu, 05 Jun 2008 13:16:54 +0100 Date: Thu, 5 Jun 2008 13:16:54 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] [PATCH 0/2] Update documentation for qemu-img + add new -B option Message-ID: <20080605121654.GE20308@shareable.org> References: <2c9e3f91af3dc46f86cdf5cf11d62512@foo> <20080604073716.GA20295@shareable.org> <20080604153953.GA31234@shareable.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Marc Bevand wrote: > On Wed, Jun 4, 2008 at 8:39 AM, Jamie Lokier wrote: > > > > - When using a relative image, you should be able to set the > > permissions on the base image to read-only. If you have a lot of > > relative images, it's really important not to modify the base > > image, and worrying that one of your QEMU processes might write to > > the base image. Virtual PC allows the base image to be read-only, > > and quite a lot of notes on Differencing stress how important it > > is to set permissions that way, if you are sharing the base. > > I have been using qemu this way for a while: hundreds of cow images > based on a small set of read-only base images (that were also > chattr +i to prevent accidents). I could have sworn qemu complained when I tried to use a read-only base image - several times. That's the basis of the above comment. But not now. Strange. Cool! :-) -- Jamie