On 02/12/2013 07:19 PM, Jeremy Linton wrote:
Ideally, Linux should not be sending task management commands to devices that
don't support the given task mgmt operation.
This patch uses the REPORT SUPPORTED TASK MGMT FUNCTIONS command to enable or
disable error recovery paths for a given device. For older devices, we make an
educated guess about what kind of error recovery the device supports. This isn't
going to be 100% accurate as it should probably take the transport as well as
the SCSI version into account, but it is a start.
While this patch improves the error recovery paths for modern SCSI networks, the
error recovery logic continues to fall through to host reset. It also continues
to send bus and target resets in cases where they may affect working devices. I
have a partial set of patches which attempt to make intelligent decisions in
these cases, but they are far more intrusive and at this point not as clear cut.
Just in case...
Signed-off-by: Jeremy Linton <jlinton@xxxxxxxxxxxxx>
Nice concept.
But unfortunately it failed the reality check; of my zoo of storage
arrays only NetApp OnTap 8.X and HP P2000 supports the
REPORT SUPPORTED TASK MANAGEMENT FUNCTIONS command.
None of the others (HP EVA, NetApp E-Series, EMC Clariion CX-3) do.
So implementing this command won't buy us much, as it'll default to
the original behaviour for most cases ...
(Not prejudicing any market share here, of course :-)
Too bad.
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)
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