RE: iSCSI: Flow Control

[Joshua Tseng <jtseng@NishanSystems.com>]

David,

<snip..snip>

>be any more expensive and it is definately safer. Well one other
>case can occur is if the initiator wants the target to issue an RTT
>and it interposes another command before the RTT is received, this
>too seems like a broken things to do as I don't see much value in doing RTT
>on a single connection.

Not doing RTT means each write command must be completed atomically
before proceeding on to the next command.  There will be some very
large data PDU's hogging the single connection.  How about task
management functions which the initiator may want to deliver
asynchronously?  With a large data PDU stuck in the connection,
(and commands stuck in the pipeline) it may require a more
catastrophic abort/reset of the entire TCP connection, which might
not have been originally necessary.

Somehow, it seems to me that the SCSI folks put RTT in there for 
a purpose, and iSCSI would be losing something by eliminating it.
I don't know exactly what this is, but I would think it includes
AT LEAST some performance impact.

Josh