From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: Scsi Error handling query Date: Mon, 30 Mar 2015 17:12:57 +0200 Message-ID: <551967F9.9020500@suse.de> References: <5d00e10b067fd4d0fb82ecdec18dd325@mail.gmail.com> <55142C6D.1060205@suse.de> <55157F08.3070707@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor2.suse.de ([195.135.220.15]:37019 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752488AbbC3PM7 (ORCPT ); Mon, 30 Mar 2015 11:12:59 -0400 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Kashyap Desai , linux-scsi@vger.kernel.org On 03/30/2015 01:45 PM, Kashyap Desai wrote: >> -----Original Message----- >> From: Hannes Reinecke [mailto:hare@suse.de] >> Sent: Friday, March 27, 2015 9:32 PM >> To: Kashyap Desai; linux-scsi@vger.kernel.org >> Subject: Re: Scsi Error handling query >> >> On 03/26/2015 07:43 PM, Kashyap Desai wrote: >>>> -----Original Message----- >>>> From: Hannes Reinecke [mailto:hare@suse.de] >>>> Sent: Thursday, March 26, 2015 9:28 PM >>>> To: Kashyap Desai; linux-scsi@vger.kernel.org >>>> Subject: Re: Scsi Error handling query >>>> >>>> On 03/26/2015 02:38 PM, Kashyap Desai wrote: >>>>> Hi Hannes, >>>>> >>>>> I was going through one of the slide posted at below link. >>>>> >>>>> http://events.linuxfoundation.org/sites/events/files/slides/SCSI-= EH. >>>>> pd >>>>> f >>>>> >>>>> Slide #59 has below data. I was trying to correlate with latest >>>>> upstream code, but do not understand few things. Does Linux handl= e >>>>> blocking I/O to the device and target before it actually start >>>>> legacy EH >>>> recovery ? >>>> >>>> Yes. This is handled by 'scsi_eh_scmd_add()', which adds the comma= nd >>>> to the internal 'eh_entry' list and starts recovery once all >>>> remaining outstanding commands are completed. >>> >>> Thanks Hannes..! Scsi_eh_scmd_add() move shost state to recovery, s= o >>> it means blocking further IO to the Host and not really a limited = to >>> Device/Target for which command was timed out. Right ? >>> I understood that, new improvement of scsi error handling will allo= w >>> IOs to the other Devices attached to the host except the IO belongs= to >>> specific target. >>> >>> Also, one more thing to clarify... In presentation, term "task set >>> aborts" >>> was used. Does this mean task set abort is handled as traversing >>> complete list of timed out command and sending individual TASK ABOR= T ? >>> >> No. The idea was to send 'task set aborts' as a single TMF. >=20 > Thanks Hannes.! OK so idea was to have single TMF for "Task set abor= t." I > am not sure how to frame my next question.. But what if Linux SCSI l= ayer > traverse each IO of one particular target and issue individual Task a= bort? > Don=E2=80=99t we call that as "task set aborts" ? How LLD Driver sho= uld interface > for "task set aborts" as single TMF ? My understanding is "Task set a= bort" > will be internally converted to single Task abort either by SCSI laye= r or > HBA FW. >=20 Why? There _is_ a 'task set abort' TMF defined in SAM. If the firmware doesn't implement it I'd thought the respective command to be failed? However, at this point I'm not sure if 'task set abort' is actually required; it _should_ be superseded by the new 'transport reset' EH handler. On the FC side this will translate into a relogin, which will automatically abort all outstanding tasks. SAS even has a dedicated TMF IT NEXUS LOSS, which looks like it could be used here. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg GF: F. Imend=C3=B6rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N=C3=BCrnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html