ordered command retrieval by LUN

[julian_satran@il.ibm.com]

Looking back at my Haifa meeting notes I found that I owe you all
a scheme that will allow ordered command retrieval by LUN (with the net
effect
that missing commands for one LU will not affect other LUs.
And all this without having the iSCSI layer at the initiator number
commands
per LU.

Assume that for any issued command within the window the initiator
keeps a record of the LUN it was issued for (i.e. an array of LUN indexed
by the
command number - sort of).

A simple error detection, that will allow operation in cases where gaps
are at most one command,  requires only to transmit with every command the
LUN of
the previous command; the target can deliver the commands to LU even with
gaps
if the gaps are of a single command.
To cope with larger gaps the target has to issue an enquiry about the
missing commands to the initiator and get their LUNs.

The scheme is simple for 1 entry gaps but not very interesting for multiple
entry gaps.
However the sent commands array might be considered for a faster recovery
from connection failures.

Julo