On 09/13/2016 04:04 PM, James Bottomley wrote: > On Mon, 2016-09-12 at 10:20 +0200, Hannes Reinecke wrote: >> SPC-2 and SPC-3 (or later) differ in the handling of reservation >> conflict for TEST UNIT READY. SPC-2 will return 'reservation >> conflict', whereas SPC-3 will return GOOD status. >> On a mixed system with both SPC-2 and SPC-3 targets one will >> see lots of 'reservation conflict' messages from the SPC-2 system but >> no messages from the SPC-3 system when eg multipath path checkers. >> These messages might confuse the unsuspecting user although in fact >> they just signal normal operation. > > I don't agree with this: a SCSI-2 device will not get properly > configured if it's reserved by something else, so you get other strange > artifacts of this condition. > It's not about SCSI-2, it's for later arrays. See below. >> So we should not be printing out 'reservation conflict' for >> TEST UNIT READY responses. > > This doesn't sound like a good rationale to me. The way I see it, if > this message is actually useful, people would like to see it when they > get a reservation conflict. That does mean even when SCSI-2 > reservations give one where SCSI-3 would not. The other reason is that > it tells you why your device didn't get configured properly: both Test > Unit Ready and Read Capacity get conflicts with SCSI-2, whereas they do > with SPC-3+ devices (trying to forget SPC-2). > This specific issue occurred with a customer which had a mix of SPC-2 and SPC-3 arrays. So I can't just 'forget' SPC-2 :-) The system works just as designed, _except_ that one array is printing this message (the SPC-2 one) whereas the other one doesn't. So the message has zero value in this case. > You could argue that the entire message needs removing, since it's > reporting stuff that mostly only shows when systems using reservations > correctly are in operation. > Oh, I'm perfectly fine with that. I'm happy to send a patch removing that line altogether. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
