From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=54030 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OHHfB-0001o2-OI for qemu-devel@nongnu.org; Wed, 26 May 2010 10:33:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OHHaI-0007z8-S3 for qemu-devel@nongnu.org; Wed, 26 May 2010 10:27:52 -0400 Received: from mail-wy0-f173.google.com ([74.125.82.173]:48439) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OHHaI-0007yr-Lx for qemu-devel@nongnu.org; Wed, 26 May 2010 10:27:50 -0400 Received: by wyf28 with SMTP id 28so1024818wyf.4 for ; Wed, 26 May 2010 07:27:49 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <4BFD2FDF.9000005@redhat.com> Date: Wed, 26 May 2010 16:27:43 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1274091292-4812-1-git-send-email-agraf@suse.de> <4BF14CE9.5040907@suse.de> <4BF15DC8.8080104@codemonkey.ws> <201005171723.15675.paul@codesourcery.com> <4BF16E22.6090400@codemonkey.ws> <4BFC0FF6.1080005@suse.de> <20100525210113.GE1402@hall.aurel32.net> <4BFC79E8.1070700@codemonkey.ws> <20100526085248.GC21913@volta.aurel32.net> <4BFD269E.9090503@codemonkey.ws> In-Reply-To: <4BFD269E.9090503@codemonkey.ws> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH] Add cache=volatile parameter to -drive List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: kwolf@redhat.com, Alexander Graf , qemu-devel@nongnu.org, Paul Brook , hch@lst.de, Aurelien Jarno On 05/26/2010 03:48 PM, Anthony Liguori wrote: > We might get 100 bug reports about this "regression" but they concern > much less than 1 bug report of image corruption because of power > failure/host crash. A reputation of being unsafe is very difficult to > get rid of and is something that I hear concerns about frequently. True, but how many people will use cache=volatile? Nobody is going to make it the default. If a blog post appears "hey look cache=volatile will speedup your virtual machine", and gets so much momentum that people start using it and lose data because of it (which is highly hypothetical and unlikely), QEMU developers are not the ones to be blamed. > I'm not suggesting that the compile option should be disabled by default > upstream. But the option should be there for distributions because I > hope that any enterprise distro disables it. Actually it's perfectly possible that they will _enable_ it if a configure option is required to enable cache=volatile. RHEL for example doesn't support at all running qemu directly, only via libvirt. If libvirt doesn't pass cache=volatile to qemu, they're safe. (Well, virt-install uses libvirt, so it couldn't use cache=volatile either, so I admit it's not a great example). Paolo