[stgt] stgt does not preempt SCSI-2 reservations; may break MS Cluster Service failover

FUJITA Tomonori fujita.tomonori at lab.ntt.co.jp
Mon Sep 14 17:01:31 CEST 2009

On Mon, 14 Sep 2009 16:56:03 +0200
Florian Haas <florian.haas at linbit.com> wrote:

> On 2009-09-14 16:50, FUJITA Tomonori wrote:
> > On Mon, 07 Sep 2009 10:16:06 +0200
> > Florian Haas <florian.haas at linbit.com> wrote:
> > 
> >> On 09/07/2009 08:00 AM, Florian Haas wrote:
> >>> On 09/07/2009 07:58 AM, FUJITA Tomonori wrote:
> >>>> On Mon, 07 Sep 2009 07:47:32 +0200
> >>>> Florian Haas <florian.haas at linbit.com> wrote:
> >>>>
> >>>>>> What iSCSI initiator implementation do you use on Linux?
> >>>>> For testing? I use open-iscsi on Debian lenny; the Debian package
> >>>>> version number is 2.0.870~rc3-0.4. My sg3-utils package version (if
> >>>>> that's of any help) is 1.24-2.
> >>>> That's strange. open-iscsi doesn't send TARGET_REST.
> >>> Interesting. Let me grab a packet dump and I'll be back in touch.
> >> You're right, open-iSCSI apparently simply translates any host or "bus"
> >> reset into a new login sequence. For device resets, it does use a Task
> >> Management Function (0x02) of the type "LU reset" (0x05).
> > 
> > Mike posted a patch to add WARM_RESET support to open-iscsi. I lightly
> > tested my patch to add TARGET_RESET to tgt and it seems to work.
> > 
> > FYI, sg_reset utility doesn't send TARGET_RESET so you need to modify
> > it.
> Then out of curiosity, how did you test TARGET_RESET when working over
> open-iscsi?

I modified sg_reset.c to issue SG_SCSI_RESET_TARGET ioctl.

> >> Going back to my original problem, I've now sifted through packet traces
> >> generated on the production iSCSI target server (the one that the MSCS
> >> hosts talk to), and have encountered something that leaves me
> >> confounded. This applies to both IET and STGT (hence yet another
> >> cross-post to both lists), so it's either something that is wrong in
> >> both implementation, or some breakage in MSCS. Perhaps someone can
> >> enlighten me here.
> > 
> > Have you tried the latest git tree (the CAPACITY bug was fixed)?
> Yes the capacity read seems to work OK now. Thanks. There still seems to
> be an additional issue with regard to "bus resets" from the MS
> initiator, but we're currently still investigating whether it's an
> initiator or target issue.

Ok, I thought that a CAPACITY READ command is successful, then the
initiator sends TARGET RESET.

Let me know if you find a issue on the target side or add a workaround
to avoid initiator issues.
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