|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] iSCSI: unsolicited dataJulian, I don't recall the earlier discussion being conclusive on this topic, so let me attempt to make a couple of suggestions on this. Last para in Section 2.2.5 (page 33) in rev09 mandates unsolicited data ordering with the following wording. "iSCSI initiators and targets MUST also enforce some ordering rules to achieve deadlock-free operation. Unsolicited data MUST be sent on every connection in the same order in which commands were sent. A target receiving data out of order SHOULD terminate the session." I have a couple of suggestions to reword - - The reference to a deadlock is true only for an implementation overcommitting the unsolicited data buffers. So, I would suggest dropping this reasoning. - The "MUST enforce" wording should also add that "targets MAY however see unexpected unsolicited data (UUD), following data digest errors on expected unsolicited data." - Finally, the "SHOULD terminate the session", IMHO, is too strong. This wording will imply that a session is vulnerable to a single digest error regardless of recovery level. [ I however disfavor attaching more assorted semantics to recovery levels (than the current easily understood "level = setof(recovery classes)" formulation). ] As you mentioned on this discussion earlier, a UUD is a protocol error (or may be not, if it is the effect of a prior digest failure). We can choose to Reject ("protocol error") the UUD and discard the data. The only problem with this approach is: following a digest error on unsolicited data for one task, all the following unsolicited data in flight would have to be discarded. One option is to imply that the target update the "expected unsolicited data" so the unsolicited data following in the pipe can be processed normally. So, I guess it would be saying: "the target MAY Reject the UUD". Comments? -- Mallikarjun Mallikarjun Chadalapaka Networked Storage Architecture Network Storage Solutions Organization MS 5668 Hewlett-Packard, Roseville. cbm@rose.hp.com
Home Last updated: Mon Dec 03 13:17:46 2001 7983 messages in chronological order |