RE: iSCSI : digest error handling violates EMDP/InDataOrder

[Robert Snively <rsnively@Brocade.COM>]

Seems to me that there are some unclarities in this area as well.

There are really two pieces being discussed as one:

	EMDP (a SCSI functionality)

	Random relative offset (a transport functionality)

EMDP is used to allow a target to request or deliver its data
out of order.  This is used for things like passing a stripe
segment from a RAID data extent as soon as it has been accumulated,
rather than waiting until all previous parts of the RAID data
extent have also been accumulated and delivered.  It is also used
for things like "start anywhere" reading of a disk track.

It says nothing about the ordering of data within a PDU or sequence
which must be ordered according to the rules of the protocol.  Fibre
Channel allows the data within a sequence to be transmitted in order
or out of order by using the login parameter "random relative offset".
Almost all devices choose to login and require "continuously increasing
relative offset".