On 01/24/2013 01:19 AM, Bart Van Assche wrote:
On Fri, Jan 18, 2013 at 9:27 AM, Ewan D. Milne <emilne@xxxxxxxxxx> wrote:
This patch set adds changes to the SCSI mid-layer, sysfs and scsi_debug
to provide enhanced support for Unit Attention conditions, as well as
detection of reported sense data overflow conditions and some changes
to sense data processing. It also adds a uevent when the reported
capacity changes on an sd device.
There was some discussion about this a couple of years ago on the linux-scsi
mailing list: http://marc.info/?l=linux-scsi&m=129702506514742&w=2
Although one approach is to send all SCSI sense data to a userspace daemon
for processing, this patch set does not take that approach due to the
difficulty in reliably delivering all of the data. An interesting UA
condition might not be delivered due to a flood of media errors, for example.
The mechanism used is to flag when certain UA ASC/ASCQ codes are received
that report asynchronous changes to the storage device configuration.
An appropriate uevent is then generated for the scsi_device or scsi_target
object. An aggregation mechanism is used to avoid generating uevents at
too high a rate, and to coalesce multiple UAs reported by LUNs on the
same target for a REPORTED LUNS DATA HAS CHANGED sense code.
Does this patch series add a function that allows SCSI LLDs to report
AEN data to the SCSI core ? What if a SCSI target reports a LUN
inventory change via AER to e.g. the iSCSI initiator and that
initiator ignores the AEN data ? Will that result in AEN data being
ignored and no automatic LUN rescanning ?
Well, first and foremost we _don't_ have automatic LUN rescanning.
This patchset just puts in the infrastructure that userspace can
know _when_ a LUN rescan might be in order.
As for AEN, does iSCSI _do_ AEN? I thought it got removed ...
If it does, though, it should schedule an event on its own whenever
an AER is received. The same goes for LLDDs with vendor-specific
AENs; thinking of megaraid_sas here ...
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
