From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:49701) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TaNlz-0006Nv-Lq for qemu-devel@nongnu.org; Mon, 19 Nov 2012 04:36:14 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TaNlw-0001Ju-JA for qemu-devel@nongnu.org; Mon, 19 Nov 2012 04:36:11 -0500 Received: from mail.profihost.ag ([85.158.179.208]:58545) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TaNlw-0001Jl-9T for qemu-devel@nongnu.org; Mon, 19 Nov 2012 04:36:08 -0500 Message-ID: <50A9FD86.3050400@profihost.ag> Date: Mon, 19 Nov 2012 10:36:06 +0100 From: Stefan Priebe - Profihost AG MIME-Version: 1.0 References: <589082222.7272963.1352241778123.JavaMail.root@redhat.com> <50A95A6A.4010109@profihost.ag> <50A9E991.2070609@redhat.com> In-Reply-To: <50A9E991.2070609@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] scsi-hd with discard_granularity and unmap results in Aborted Commands List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org Hi Paolo, Am 19.11.2012 09:10, schrieb Paolo Bonzini: >> I'm sorry the discard requests aren't failing. Qemu / Block driver >> starts to cancel a bunch of requests. > > That is being done in the kernel (the guest, I think) because the UNMAPs > are taking too long. That makes sense. RBD handles discards as buffered I/O. When i do an mkfs.xfs on a 30GB device i see around 900 pending discard requests. rbd finishes them all before reporting success. If it is correct that a 3.6.7 kernel sends as many discard requests i only the a solution in using unbuffered I/O for discards. Do you know what is the correct way? Greets, Stefan