On Wed, 2021-04-28 at 11:01 +1000, Erwin van Londen wrote: > > The way out of this is to chuck the array in the bin. As I mentioned > in one of my other emails when a scenario happens as you described > above and the array does not inform the initiator it goes against the > SAM-5 standard. > > That standard shows: > 5.14 Unit attention conditions > 5.14.1 Unit attention conditions that are not coalesced > Each logical unit shall establish a unit attention condition whenever > one of the following events occurs: > a) a power on (see 6.3.1), hard reset (see 6.3.2), logical > unit reset (see 6.3.3), I_T nexus loss (see 6.3.4), or power loss > expected (see 6.3.5) occurs; > b) commands received on this I_T nexus have been cleared by > a command or a task management function associated with another I_T > nexus and the TAS bit was set to zero in the Control mode page > associated with this I_T nexus (see 5.6); > c) the portion of the logical unit inventory that consists > of administrative logical units and hierarchical logical units has > been changed (see 4.6.18.1); or > d) any other event requiring the attention of the SCSI > initiator device. > > Especially the I_T nexus loss under a is an important trigger. > > --- > 6.3.4 I_T nexus loss > An I_T nexus loss is a SCSI device condition resulting from: > > a) a hard reset condition (see 6.3.2); > b) an I_T nexus loss event (e.g., logout) indicated by a Nexus Loss > event notification (see 6.4); > c) indication that an I_T NEXUS RESET task management request (see > 7.6) has been processed; or > d) an indication that a REMOVE I_T NEXUS command (see SPC-4) has > been processed. > An I_T nexus loss event is an indication from the SCSI transport > protocol to the SAL that an I_T nexus no > longer exists. SCSI transport protocols may define I_T nexus loss > events. > > Each SCSI transport protocol standard that defines I_T nexus loss > events should specify when those events > result in the delivery of a Nexus Loss event notification to the SAL. > > The I_T nexus loss condition applies to both SCSI initiator devices > and SCSI target devices. > > If a SCSI target port detects an I_T nexus loss, then a Nexus Loss > event notification shall be delivered to > each logical unit to which the I_T nexus has access. > > In response to an I_T nexus loss condition a logical unit shall take > the following actions: > a) abort all commands received on the I_T nexus as described in 5.6; > b) abort all background third-party copy operations (see SPC-4) that > are using the I_T nexus; > c) terminate all task management functions received on the I_T nexus; > d) clear all ACA conditions (see 5.9.5) associated with the I_T > nexus; > e) establish a unit attention condition for the SCSI initiator port > associated with the I_T nexus (see 5.14 > and 6.2); and > f) perform any additional functions required by the applicable > command standards. > --- > > This does also mean that any underlying transport protocol issues > like on FC or TCP for iSCSI will very often trigger aborted commands > or UA's as well which will be picked up by the kernel/respected > drivers. Thanks a lot. I'm not quite certain which of these paragraphs would apply to the situation I had in mind (administrator remapping an existing LUN on a storage array to a different volume). That scenario wouldn't necessarily involve transport-level errors, or an I_T nexus loss. 5.14.1 c) or d) might apply, is that what you meant? Regards Martin -- Dr. Martin Wilck <mwilck@xxxxxxxx>, Tel. +49 (0)911 74053 2107 SUSE Software Solutions Germany GmbH HRB 36809, AG Nürnberg GF: Felix Imendörffer
