Re: iSCSI: Recovery R2T

[Michael Morrison <mmorrison@istor.com>]

Mallikarjun,

Your definition looks OK to me.  But I'm concerned about the case of DataSequenceInOrder
being set to Yes.  The R2T text allows the target to send a recovery R2T, but the
text in 11.20 says that the initiator cannot send the requested data as it's not a continuously non-decreasing offset.  

From 9.8 (R2T)
 DataSequenceInOrder governs the buffer offset ordering in consecu-
   tive R2Ts. If DataSequenceInOrder is Yes, then consecutive R2Ts
   SHOULD refer to continuous non-overlapping ranges.

From 11.20
If DataSequenceInOrder is set to Yes, Data Sequences MUST be trans-
   ferred using continuously non-decreasing sequence offsets (R2T buffer
   offset for writes, or the smallest SCSI Data-In buffer offset within
   a read data sequence).

Mike

On Fri, 2002-07-12 at 10:31, Mallikarjun C. wrote:
> Michael,
>
> It appears to me that we need to define the term `recovery R2T' - 
> the lack of which David Black also pointed out earlier.
>
> Here's what I propose we should define it as:
>
> Recovery R2T: It is an R2T generated by a target upon detecting 
> the loss of one or more Data-Out PDUs through one of the following means
> - a digest error, a sequence error, or a sequence timeout.  A recovery
> R2T carries the next unused R2TSN, but requests part of or the entire
> data 
> burst that an earlier R2T (with a lower R2TSN) had already requested.
>
> I believe the MUST/SHOULD/MAY language contained in Section 6 already 
> defines the expectations on the usage scope of recovery R2T.
> -- 
> Mallikarjun 
>
>
> Mallikarjun Chadalapaka
> Networked Storage Architecture
> Network Storage Solutions
> MS 5668	Hewlett-Packard, Roseville.
> cbm@rose.hp.com
>
>
> > Michael Morrison wrote:
> > 
> > 
> > 
> > If an initiator sends multiple Data-Out in response to an R2T, and one
> > of the Data-Out in the
> > sequence has a data digest error, can the recovery R2T solicit only
> > the missing data, or must
> > it solicit the whole sequence?   I can't find anything in the draft
> > that defines what the contents
> > of a recovery R2T MUST/SHOULD/MAY contain.
> > 
> > Thanks
> > Michael Morrison
> > ISTOR Networks
> > 7585 Irvine Center Dr. Ste 250
> > Irvine Ca. 92618
> > PGP Key: 74C30155
>

Michael Morrison
ISTOR Networks
7585 Irvine Center Dr. Ste 250
Irvine Ca. 92618
PGP Key: 74C30155