From mboxrd@z Thu Jan 1 00:00:00 1970 From: Spelic Subject: How to reissue stuck inflight i/o Date: Tue, 26 Nov 2013 18:54:14 +0100 Message-ID: <5294E046.409@shiftmail.org> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids Hello all, we just had a case in which some I/Os were apparently stuck inflight in an LV aka DM (visible in iostat as nonzero avgqu-sz for an dm-X device) for a long time, such as at least 20 minutes, but all layers below it had zero inflight I/O (MD RAID and then the disks), so DM and the above layers were waiting endlessly. This was with an old kernel 2.6.24-something . I wasn't able to debug further. After 30 minutes or so it resolved by itself without leaving anything in dmesg or anywhere else. Is there a way to reissue inflight I/O to lower layers (such as what happens transparently with the 5 SCSI retries after SCSI timeout) for DM, or at least kill such I/O so that above layers receive an I/O error and move on? I was thinking at some dmsetup command but was not clear to me which. What about a dmsetup suspend and then resume? I didn't think about trying this, at that time. Thanks S.