FC-Tape Minutes Feb 10-11,1999 Huntington Beach, CA

STEWART_R_WYATT at HP-Boise-om2.om.hp.com STEWART_R_WYATT at HP-Boise-om2.om.hp.com
Fri Feb 12 19:39:17 PST 1999

* From the T10 Reflector (t10 at symbios.com), posted by:
* STEWART_R_WYATT at HP-Boise-om2.om.hp.com
     Joint T11/T10 FC-TAPE AdHoc Meeting              T11/99-104v0          
     February 10/11, 1999 Huntington Beach, California
     Stewart Wyatt, HP - Secretary
     1. Introductions. Dale LaFollette, StorageTek, the facilitator called 
     the meeting to order just after 3 PM. As is customary, he had everyone 
     introduce themselves.
     2. Approval of this Agenda: T11/99-024v0 Group
     The agenda was approved with the following changes:
     Change Item 5. The latest draft of the profile is T11/99-069v0 (not 
     Add to item 6, Recovery on Fabrics: Dave Ford.
     Add to Item 7, Meeting requests: Group. 
     3. Approval of 12/16 Minutes: T11/98-619v0 Stewart Wyatt - Approved
     4. Review of Old Action Items: Stewart Wyatt
     Action items from Novembers T10 meetings
     #1 Erich Oetting will propose to the T10 working group that the Write 
     Exclusive Persistent Reservations be made illegal for SSC devices. 
     #3 Erich Oetting will propose to the T10 working group that the 
     communications devices command set be made obsolete. Completed
     #4 Dave Peterson will attempt to document EOD behavior more precisely 
     in the SSC.Dave has posted a new version of the SSC, deferred to the 
     next T10 meeting
     Action Items from Decembers T11 meetings
     #1 Dave Peterson: Public/Private Loop authentication annex. Dave 
     concluded this issue was adequately documented in the FLA. See 
     discussion below.
     5. FC-TAPE Document Review: T11/98-124vD (Corrected to T11/99-069v0) 
     Dave Peterson
     #1. SUN - Bob Snively, Comment # 20. "Remove clause 6.3 Loop 
     Initialization features". This clause is labeled as "informational". 
     The group agreed to remove it and insert a sentence that states that 
     the initialization features required by FC-Tape will be defined by 
     #2. Seagate - Paul Suhler, Comment #6 "Prohibit recover buffer data 
     command". Currently the profile requires support of this command. Paul 
     Suhler pointed out that it is not used in Seagate drives. Stewart 
     Wyatt said that HP drives don't use it either. Dale asked if it could 
     be retained as an allowed command. Bob Snively saw it as a feature 
     that was used in older systems to recover data from the buffer when 
     the drive ran out of media during a write. Modern systems have other 
     means of avoiding this problem. Dale LaFollette thought it was useful 
     for slow drives with large buffers with immediate command reporting. 
     Bob argued that either every drive should implement the command or 
     none should so that the host could use a common driver. Matt Wakeley, 
     HP, argued that the host should keep a copy of the data in its buffer 
     anyway so that this means of recovery should be unnecessary. The 
     conclusion was to prohibit the recovered buffer data command, leaving 
     an entry for it in the table, and add a comment that a host is 
     required to keep a copy of the data until it is assured the data is 
     safely on the media.
     #3. LSI - Charles Binford, Comment #13, "Limit data overlay to error 
     recovery". This comment was rejected in the last meeting in Charles 
     absence. Since Charles was in attendance, the editor brought it up for 
     review. Charles is concerned that with data overlay it is difficult 
     for the host to tell that it has received all of the data. He was 
     specifically worried that an entire sequence could be lost in a 
     multiple sequence read operation. One solution would be to require 
     continuously increasing sequence count. FC-PH requires this feature 
     with streamed sequences, but the PLDA did not require it for the 
     FCP_RSP since existing initiators didn't support it.
     During error recovery, the host sends an SRR requesting retransmission 
     of the data. The current profile allows the target to begin the 
     transfer at any point before the requested offset at the targets 
     convenience. This makes it difficult for the host to ensure that all 
     of the data has been received since current designs rely on counting 
     the bytes received and comparing that to the amount requested. If the 
     target sends more data than was requested, the existing host solutions 
     become confused.
     Dave Baldwin, Emulex, and Matt Wakeley, HP, agreed with Charles. Matt 
     noted that he needs to allocate buffer space before sending the SRR 
     and doesn't want the target to send more data than the space he has 
     Editor Dave Peterson saw these arguments as a violation of fundamental 
     SCSI behavior. He felt that the hosts should use the relative offset 
     of the buffer to check the data not the number of bytes transferred. 
     He referred to the SCSI modify data pointer operation and was 
     concerned that data integrity was being compromised by the existing 
     host solutions.
     Bob Kembel, Connectivity Solutions and others pointed out that 
     parallel SCSI does not have a recover read data capability so that 
     there is no precedence in SCSI for this situation.
     Dal Allan, ENDL, noted that the issue boiled down to making life hard 
     for targets or for initiators. He and others felt it was important to 
     find a solution that could use existing hardware. The proposed 
     solution was to require the target to begin error recovery on the 
     precise boundary required by the host, assuming the target could begin 
     recovery at some earlier boundary and bit bucket the extra data. This 
     proposal was approved by a 8 to 1 vote.
     The conclusion was to require targets to start recovery on the at the 
     exact offset requested by the host. Targets are also required to use 
     continuously increasing sequence count on streamed reads including the 
     response. Initiators are expected to check for this functionality 
     thought the profile will be silent on this as some initiators are not 
     currently capable of checking it. Finally data overlay will only be 
     allowed in response to an SRR.
     # 4 LSI - Charles Binford, Comment # 16 "wrong length for additional 
     Charles became confused when he reviewed the PLDA requirements for 
     FCP_RSP when he saw what appeared to him as inconsistencies. These 
     were explained by PLDA editor Bob Kimball who was present.
     Dale LaFollette thought the issue was over the buffer size required 
     for the host to receive auto sense. Fibre Channel is different than 
     parallel SCSI since it requires auto sense. The host has to allocate 
     adequate buffer space for the auto sense data for every command it 
     issues. The issue is the maximum FCP_RSP frame that the host could 
     expect to receive given the minimum frame buffer size. Dale notes that 
     this was settled by this group long ago by asking targets how much 
     sense data that they would send, less than 128. The minimum size has 
     increased from 128 to 256.
     Charles retracted his comment. Bob Kembel noted that for 256 byte 
     frame the maximum sense space is 224 bytes. Dale and Charles agreed 
     that restricting the size of the response frame is good and the 
     current requirement is correct. The group rejected the comment, but 
     table will be clarified anyway.
     #5 Sun Bob Snively - Comment, "Add a data overlay bit for error 
     recovery in PRL.".
     Dave Baldwin, Emulex, wants a FC-Tape compliance bit in the PRLI.
     Charles Binford wants CRN support bit in the inquiry data.
     Dave Baldwin wants a FC-Tape compliance in the inquiry also.
     Bob Snively, Dave Baldwin and George Penokie, IBM got into a long 
     discussion about ports, targets, LUNs and whether this should be in 
     mode pages, inquiry data or PRLI. George seemed to think something new 
     needed to be invented. No resolution was reached.
     #6 LSI - Charles Binford Comment # 25 "R_A_TOV instead of E_D_TOV". 
     Charles noted that the profile incorrectly assumed that E_D_TOV would 
     be used to time ELS replies. It should be 2 times R_A_TOV. Since 
     R_A_TOV is specified by the Fabric, the value should be a reasonable.
     Since the error recovery (clause 9 in previous drafts of the profile) 
     is being moved to the FCP2 the issue was deferred to Bob Snively.
     #7 Dave Ford, Clariion, had requested to make a presentation and was 
     invited to do so. Dave presented several slides discussing the need 
     for targets to recover resources from failed initiators in a fabric 
     environment. His proposed solution was for targets to implement 
     timeouts. His presentation was cut short when it was noted that the 
     timeouts are already a requirement in the profile. 
     #8 Public loop authentication was discussed. This was the action item 
     that Dave Peterson had from the last meeting to document the 
     authentication process. On review of the FLA, Dave thought the issue 
     was adequately documented. Questions from the participants could not 
     find a need for additional documentation so the issue was dropped
     #9 Connectivity Solutions - Bob Kimball Comment #15, "Requirement for 
     loop port to recognize alias of x'00 00 AL_PA'". The comment was 
     addressed in the FC-AL2 standard.
     # 10 Connectivity Solutions - Bob Kimball Comment # 48, "FCP_CMND 
     Bob objected to the requirement for polling with REC at a specific 
     rate. He felt that the host should not be forced to poll at exactly 
     that rate. The group agreed to change the definition from a precise 
     value to a minimum rate.
     #11 Connectivity Solutions - Bob Kembel "Transfer of Sequence 
     Initiative by SRR".
     Bob Kembel sees this function as a fundamental architectural change. 
     He thought a better solution would be a basic link service that 
     changed initiative. Bob Snively agreed that it may cause problems for 
     automated chips. Stewart Wyatt suggested that the change of sequence 
     initiative could be indicated by a No-Op basic link service.
     This issue was left open for additional thought and investigation.
     #12 Connectivity Solutions - Bob Kembel Comment #56, "SCSI-specific 
     behavior of SRR".
     Bob thought that the SRR contained SCSI specific behavior and should 
     have Type = x'08'. Since the FC-FS will be documenting all ELS he 
     thought a more generic description might be needed. A discussion 
     followed about whether SRR was indeed SCSI specific or could be used 
     in other protocols. Bob Snively said he would look at the issue and 
     would move the description to an annex in FCP2 for inclusion later in 
     At this point the group broke for the evening - Q-Logic was sponsoring 
     a reception and food was available!
     February 11, 1999, the meeting resumed at 8 AM. Dave continued the 
     discussion of the letter ballots.
     # 13 SUN- Bob Snively, Comment #27, "Incorrect value for ULP_TOV".
     Bob proposed that the value be changed to "Operation specific time 
     plus two seconds". The current version of the specification is 
     "Operation specific timer + 4 x REC_TOV". This time needs to be large 
     enough that recovery from an error can complete before this timer 
     expires. The conclusion was to leave it as is. Clause 7.7 is to be 
     changed by removing the second paragraph which is redundant and 
     incorporating the note into the text.
     #14 SUN - Bob Snively, Comment #26, "Unnecessarily strict requirement 
     on NACA".
     Bob thinks that implementing ACA will create a lot of trouble. He 
     proposes changing note 3 in table 21 to read that ACA should be 
     mandatory if tagged command queuing is used which is ordered or where 
     state information queuing must be maintained. For other queuing 
     environments it is recommended.
     #15 SUN - Bob Snively, Comment #52, "Different second level error 
     Bob wants the same timeout to be used for ABTS, REC and SRR. ABTS is a 
     BLS while REC and SRR are ELS. Dave noted that FC-PH is unclear about 
     BLS timeouts. Use two times R_A_TOV for all cases.
     #16 SUN - Bob Snively, Comment #56, "Remove material provided in 
     Dave had already removed the material. Some references will be added 
     in FCP2.
     #17 SUN - Bob Snively, Comment #57, "All sections are redundant wil 
     PLDA or other documents"
     The editor has or will remove the material and will add text 
     referencing the other documents.
     #18 SUN - Bob Snively, Comment #58, "Clearing effects document s/b in 
     Accepted. The table will be moved out of FC-TAPE.
     #19 SUN - Bob Snively, Comment #59, "APTPL should be required"
     This would require tapes to save persistant reservations across power 
     cycles. Dale noted that most tapes rewind and eject the tape when they 
     are powered down. Bob asked if this was documented behavior. Bob is 
     concerned that if the drive doesn't support persistant reservations 
     that it needs to power up into a state where it has to be in an 
     initialized state (i.e. not loaded) before it accepts any commands to 
     support clustering requirements. Bob thought that this should be 
     documented in the SSC (not in FC-TAPE). Deferred to SSC.
     #20 SUN - Bob Snively, Comment #60, "Should TPRLO be made prohibited?"
     Dave Baldwin noted that this is used today to clear third party 
     reservations. Bob would prefer that persistant reservations be used. 
     Deferred for Dave Baldwin's investigation.
     #21 SUN - Bob Snively, Comment #61, " Reassignment of critical mode 
     The SCSI committee has redefined the Fibre Channel mode pages. Bob 
     also wants to consider which parameters should be invocable or 
     prohibited. Bob proposed eliminating all of the options except EMDP 
     and Maximum Burst Size. This was accepted.
     #22 StorageTek, Comment #36. This proposal is to change the title of 
     the profile to include media changers, "Fibre Channel Tape and Tape 
     Media Changer (FC-TAPE). Accepted.
     #23 LSI - Charles Binford, Comment #31, "SEQ_CNT in ABTS accept 
     Charles thought the Lowest SEQ_CNT value does not consider all of the 
     cases. Some members of the group thought that the profile should 
     reference FC-PH and not include the marterial at all. Bob Kembel noted 
     that the material is difficult to decipher in FC-PH and so was 
     included in PLDA. This reference occurs in the error recovery clause 
     that is being moved to FCP-2. Decided to refer to FC-PH
     #24 Connectivity Solutions - Bob Kembel, Comment #29, "Response to 
     selected link services".
     Bob notes that Fibre Channel allows link services before PLOGI. PLDA 
     and now FC-TAPE have prohibited any link services before completed 
     login. Bob suggested some cases where allowing some link services 
     before login is completed. One example is error recovery on a failed 
     login. Deferred.
     6. T11 New Business: Group
     7. T10 New Business: Group
     7.1 SSC-2 Dave Peterson
     7.2 FCP-2 Bob Snively
     New business
     Goal was to complete review of comments by April. The editor suggested 
     he would like to get as much time as he could get. Bob Snively wants 
     some time for FCP-2. There is also some SSC business to complete as 
     8. Review New Action Items: Stewart Wyatt
     #1. Dave Peterson/Bob Snively - Update the error recovery 
     documentation to resolve the timeout for ELS.
     #2. Group - Resolve the issue of signalling support for FC-Tape error 
     recovery, CRN support and data overlay in either/or inquiry data, mode 
     pages, PRLI or by some other means.
     #3. Group - Consider the effects of transferring sequence initiative 
     by means of the SRR. Is there a better way?
     #4. Bob Snively - Consider whether SRR is SCSI specific. But in an 
     annex in FCP2 for inclusion later in the FC-FS.
     #5. Dave Peterson - Report the ommision of BLS timeout in FC-PH.
     #6. Dave Peterson - Consider modifying the tape model to require that 
     the tape power up uninitialiized, unloaded state. SSC
     #7. Dave Baldwin - Investigate eliminating TPRLO.
     #8 Dave Peterson/group - Resolution of need for authentication 
     9. Adjournment: Group

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