Re: iSCSI: ISIDs

[Sandeep Joshi <sandeepj@research.bell-labs.com>]

David,

Black_David@emc.com wrote:
> This is primarily an issue for recovery of session-associated resources
> like Persistent Reserves.  There's no free lunch here - it's necessary
> to remember where these were put (which session) in order to get them
> back.  It can also help to get old sessions removed from the Target
> faster.  If the initiators remember TSIDs, this all works - is there
> an important difference for implementations in remembering dynamically
> assigned TSIDs vs. statically assigned ISID ranges?

You have tackled every question except the one you have raised 
here and in a previous email :-)

..Is it a big difference for the initiator to remember a
dynamically assigned ID ?

Most hardware-based HBAs should have probed the network
and discovered existing targets before the OS does its SCSI scan.
In which case the HBA would have some persistent on-board memory
as it cannot expect the OS to provide the ISIDs from
some file or registry _before_ the SCSI scan.  Hence I dont see
a problem with the hardware-based HBA remembering an ID.

As regards software-based initiators, they would be expected
to initialize only after the OS (partly) initializes in which 
case they would have access to some "file" which could contain 
the IDs.

I may be wrong here..but this point deserves some discussion from
the people with cross-OS expertise if we are to go with 
target-assigned IDs scheme.

thanks
-Sandeep