On 03/27/2014 07:49 AM, Christoph Hellwig wrote:
On Tue, Dec 10, 2013 at 12:05:12PM +0100, Hannes Reinecke wrote:
Sequential scan for more than 256 LUNs is very fragile as
LUNs might not be numbered sequentially after that point.
SAM revisions later than SCSI-3 impose a structure on
LUNs larger than 256, making LUN numbers between 256
and 16384 illegal.
SCSI-3, however allows for plain 64-bit numbers with
no internal structure.
So restrict sequential LUN scan to 256 LUNs and add a
new blacklist flag 'BLIST_SCSI3LUN' to scan up to
max_lun devices.
What do you need the blacklist flag for? There's no user of it, and
supporting that many LUNs without REPORT LUNS support doesn't sound very
practical anyway.
Because there is no guarantee that pre-SCSI-3 devices (or devices
announcing to be pre-SCSI-3) will not allow to scan more than 256 devices.
Thinking of older Symmetrix here with their weird 'SPC-3 masking as
SCSI-2' habit.
Also currently we're allowing to scan beyond 256 without any
restrictions there might be installations out there which rely on this
behaviour.
Hence this flag.
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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