From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42388) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yq1HU-0008R9-QQ for qemu-devel@nongnu.org; Wed, 06 May 2015 11:30:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yq1HT-0001Ib-39 for qemu-devel@nongnu.org; Wed, 06 May 2015 11:30:40 -0400 Sender: Paolo Bonzini Message-ID: <554A3395.7050509@redhat.com> Date: Wed, 06 May 2015 17:30:29 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1426791801-9042-1-git-send-email-mreitz@redhat.com> <20150505094606.GB29818@stefanha-thinkpad.redhat.com> <554A1160.7020200@redhat.com> In-Reply-To: <554A1160.7020200@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 0/3] block: Warn about usage of growing formats over non-growable protocols List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz , Stefan Hajnoczi Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, Stefan Hajnoczi On 06/05/2015 15:04, Max Reitz wrote: >> >> Introducing a warning for a normal QEMU invocation is a bit weird. >> >> What is the point of this series? Were users confused that they hit >> ENOSPC? > > Users were confused when exporting a qcow2 image using nbd-server > instead of qemu-img, and then accessing that NBD export with qemu > (subsequently getting I/O errors on guest writes, if the image is not > yet fully allocated): http://bugzilla.redhat.com/show_bug.cgi?id=1090713 I think NBD exports of non-raw images falls within the case of "user should know what they're doing". In particular, you don't even need metadata preallocation, you just need a "truncate -s10G file.qcow2" before invoking nbd-server. So I think it's not worth fixing this, even though I see how it can be a minor UI/UX issue. Paolo