From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:49204) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RIF3D-0006l1-Jx for qemu-devel@nongnu.org; Mon, 24 Oct 2011 03:34:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RIF3C-0005Vh-5W for qemu-devel@nongnu.org; Mon, 24 Oct 2011 03:34:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55389) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RIF3B-0005VL-Bj for qemu-devel@nongnu.org; Mon, 24 Oct 2011 03:34:25 -0400 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p9O7YMDK029563 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 24 Oct 2011 03:34:22 -0400 Message-ID: <4EA515B9.8070204@redhat.com> Date: Mon, 24 Oct 2011 09:37:29 +0200 From: Kevin Wolf MIME-Version: 1.0 References: <1319216912-26964-1-git-send-email-kwolf@redhat.com> <4EA1BD95.8030205@redhat.com> In-Reply-To: <4EA1BD95.8030205@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/2] block: Write out internal caches even with cache=unsafe List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org, avi@redhat.com Am 21.10.2011 20:44, schrieb Paolo Bonzini: > On 10/21/2011 07:08 PM, Kevin Wolf wrote: >> Avi complained that not even writing out qcow2's cache on bdrv_flush() made >> cache=unsafe too unsafe to be useful. He's got a point. > > Why? cache=unsafe is explicitly allowing to s/data/manure/ on crash. It's surely expected on a host crash, but is it for a qemu crash? cache=unsafe was introduced to avoid fsync() costs, which it still does after this patch. > If you do this for raw-posix, you need to do it for all protocols. rbd could use it, too, right. Any other protocol I missed? Kevin