Re: iSCSI error recovery

[Santosh Rao <santoshr@cup.hp.com>]

YP,

Y P Cheng wrote:

> With a single CRC covering both the frame header and payload, when a bad
> frame is thrown away which is the only one in a sequence, the only way for
> detecting the missing frame is timeout.

Not true for a Data PDU. An I/O timeout only occurs when the Status PDU is
discarded due to a CRC error [or format error]. Discarding a Data PDU [due to a
CRC error or format error] results in I/O underrun, [a terminology used to
describe initiator receiving less data than sent by target] and can be detected
by a count check . [using a DataSN based count as described by Julian in his
last clarification on this issue.]

If the Data PDU also contained the Status within, then discarding such a PDU
does cause an I/O timeout.

Regards,
Santosh
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