[Scst-devel] More than 256 LUNS in SCST

[sandip s. <san...@gm...>]

Hi Guys,


       I was looking at the SCST code path to see if it will support more
than 256 LUNs.
       Looking at the report_luns_local code path, i understand that we
support only 512 luns right now, because we are not supporting SG handling
in that function.


       Now when i went through the SPC4 docs, i understand that to support
more than 256 LUNS we need to use flat space lun addressing.
       I see that the scst_lun_unpack func, which is called from the rx code
path, does differentiate between the LUN addressing methods.
       But what i fail to understand is that, how does the initiator
understand what addressing method to use. When SCST replies to the
report_lun_command it just returns the lun id as they are stored in the
acg_dev->lun, which are 0, 1, ...
       So do we have to change the scst_report_luns_local code to change the
lun numbers greater than 256. ie. for lun number > 256 we will have to set
the  6th and 7th bits as "01" ?
       I have a qla2340 card on both the initiator and target. I also went
through the BIOS settings for qlogic which had a limit of 255 LUNS on a
device. So does that mean that the lun id interpretation will be done at the
FC level rather than the SCSI layer ?


       Also i am interested in knowing whether SCST is planning to support
multiple target devices. i.e. can we have some changes so that the intiator
sees multiple SCSI target devices rather than a single.


Thanks in advance for your help.
Sandip
-- 
What We Do In Life Echoes In Eternity.