Laurence Oberman Principal Software Maintenance Engineer Red Hat Global Support Services ----- Original Message ----- From: "Bart Van Assche" <bart.vanassche@xxxxxxxxxxx> To: "Laurence Oberman" <loberman@xxxxxxxxxx> Cc: linux-block@xxxxxxxxxxxxxxx, "linux-scsi" <linux-scsi@xxxxxxxxxxxxxxx>, "Mike Snitzer" <snitzer@xxxxxxxxxx>, "James Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>, "device-mapper development" <dm-devel@xxxxxxxxxx>, lsf@xxxxxxxxxxxxxxxxxxxxxxxxxx Sent: Monday, May 2, 2016 2:49:54 PM Subject: Re: [dm-devel] [Lsf] Notes from the four separate IO track sessions at LSF/MM On 04/29/2016 05:47 PM, Laurence Oberman wrote: > From: "Bart Van Assche" <bart.vanassche@xxxxxxxxxxx> > To: "Laurence Oberman" <loberman@xxxxxxxxxx> > Cc: "James Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>, "linux-scsi" <linux-scsi@xxxxxxxxxxxxxxx>, "Mike Snitzer" <snitzer@xxxxxxxxxx>, linux-block@xxxxxxxxxxxxxxx, "device-mapper development" <dm-devel@xxxxxxxxxx>, lsf@xxxxxxxxxxxxxxxxxxxxxxxxxx > Sent: Friday, April 29, 2016 8:36:22 PM > Subject: Re: [dm-devel] [Lsf] Notes from the four separate IO track sessions at LSF/MM > >> On 04/29/2016 02:47 PM, Laurence Oberman wrote: >>> Recovery with 21 LUNS is 300s that have in-flights to abort. >>> [ ... ] >>> eh_deadline is set to 10 on the 2 qlogic ports, eh_timeout is set >>> to 10 for all devices. In multipath fast_io_fail_tmo=5 >>> >>> I jam one of the target array ports and discard the commands >>> effectively black-holing the commands and leave it that way until >>> we recover and I watch the I/O. The recovery takes around 300s even >>> with all the tuning and this effectively lands up in Oracle cluster >>> evictions. >> >> This discussion started as a discussion about the time needed to fail >> over from one path to another. How long did it take in your test before >> I/O failed over from the jammed port to another port? > > Around 300s before the paths were declared hard failed and the > devices offlined. This is when I/O restarts. > The remaining paths on the second Qlogic port (that are not jammed) > will not be used until the error handler activity completes. > > Until we get these for example, and device-mapper starts declaring > paths down we are blocked. > Apr 29 17:20:51 localhost kernel: sd 1:0:1:0: Device offlined - not > ready after error recovery > Apr 29 17:20:51 localhost kernel: sd 1:0:1:13: Device offlined - not > ready after error recovery Hello Laurence, Everyone else on all mailing lists to which this message has been posted replies below the message. Please follow this convention. Regarding the fail-over time: the ib_srp driver guarantees that scsi_done() is invoked from inside its terminate_rport_io() function. Apparently the lpfc and the qla2xxx drivers behave differently. Please work with the maintainers of these drivers to reduce fail-over time. Bart. -- 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 Hello Bart Even in the case of the ib_srp, don't we also have to still run the eh_timeout for each of the devices that has inflight requiring error handling serially. This means we will still have to wait to get a path failover until all are through the timeout. Thanks Laurence -- 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
