From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin George Subject: Re: [PATCH] sd: always retry READ CAPACITY for ALUA state transition Date: Fri, 1 May 2015 18:09:35 +0530 Message-ID: <55437407.7060702@netapp.com> References: <1430127309-90412-1-git-send-email-hare@suse.de> <1430255925.2181.16.camel@HansenPartnership.com> <55421F70.80102@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx143.netapp.com ([216.240.21.24]:51670 "EHLO mx143.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751122AbbEAMtH (ORCPT ); Fri, 1 May 2015 08:49:07 -0400 In-Reply-To: <55421F70.80102@suse.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Hannes Reinecke , James Bottomley Cc: Christoph Hellwig , linux-scsi@vger.kernel.org On 4/30/2015 5:56 PM, Hannes Reinecke wrote: > On 04/28/2015 11:18 PM, James Bottomley wrote: >> On Mon, 2015-04-27 at 11:35 +0200, Hannes Reinecke wrote: >>> During ALUA state transitions the device might return >>> a sense code 02/04/0a (Logical unit not accessible, asymmetric >>> access state transition). As this is a transient error >>> we should just retry the READ CAPACITY call until >>> the state transition finishes and the correct >>> capacity can be returned. >>> >>> Signed-off-by: Hannes Reinecke >>> --- >>> drivers/scsi/sd.c | 10 ++++++++++ >>> 1 file changed, 10 insertions(+) >>> >>> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c >>> index 79beebf..7178b05 100644 >>> --- a/drivers/scsi/sd.c >>> +++ b/drivers/scsi/sd.c >>> @@ -1987,6 +1987,11 @@ static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp, >>> * give it one more chance */ >>> if (--reset_retries > 0) >>> continue; >>> + if (sense_valid && >>> + sshdr.sense_key == NOT_READY && >>> + sshdr.asc == 0x04 && sshdr.ascq == 0x0A) >>> + /* ALUA state transition; always retry */ >>> + continue; >>> } >>> retries--; >>> >>> @@ -2069,6 +2074,11 @@ static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp, >>> * give it one more chance */ >>> if (--reset_retries > 0) >>> continue; >>> + if (sense_valid && >>> + sshdr.sense_key == NOT_READY && >>> + sshdr.asc == 0x04 && sshdr.ascq == 0x0A) >>> + /* ALUA state transition; always retry */ >>> + continue; >>> } >>> retries--; >>> >> >> Got to say I really don't like this infinite retry possibility. How >> long does the ALUA transition take? Would increasing retries work (or >> even hijacking reset_retries)? >> > Well ... transitioning could be quite long (NetApp FAS has a > transition timeout of 30 _minutes_ ...). Well, actually NetApp FAS has a transition timeout of 2 minutes, and not 30 minutes - as reported in the IMPLICIT TRANSITION TIMEOUT value in the extended RTPG data. -Martin