Subject: RAID Study Group Minutes To: SCSI Reflector List Date: Tue, 19 Jan 93 17:50:47 MST From: John Lohmeyer Accredited Standards Committee X3, Information Processing Systems Doc. No.: X3T9.2/93-005 R0 Date: January 10, 1993 Project: Ref. Doc.: Reply to: G. Penokie To: Membership of X3T9.2 From: George Penokie, Chair RAID Study Group Subject: Minutes of RAID Study Group Meeting (1/11/93) ______________________________________________________________________________ Agenda 1. Opening Remarks 2. Attendance and Membership 3. Approval of Agenda 4. Summary of SCSI Disk Array Items Submitted in the RAID Study Group (93-002) [Penokie] 5. SCSI Disk Array Model (93-003) [Penokie] 6. Dual Array Controllers [Todd] 7. Meeting Schedule 8. Adjournment Results of Meeting 1. Opening Remarks George Penokie the RAID Study Group Chair, called the meeting to order at 3:45 pm, Monday January 10, 1993. He thanked Jim Smith of Tandem Computers for hosting the meeting. As is customary, the people attending introduced themselves. A copy of the attendance list was circulated for attendance and corrections. It was stated that the meeting had been authorized by X3T9.2 and would be conducted under the X3 rules. Ad hoc meetings take no final actions, but prepare recommendations for approval by the X3T9.2 task group. The voting rules for the meeting are those of the parent committee, X3T9.2. These rules are: one vote per company; and any participating company member may vote. The minutes of this meeting will be posted to the SCSI BBS and the SCSI Reflector and will be included in the next committee mailing. George stated that this is the third meeting of the RAID study group. The purpose of the group is to deal with interface issues related to using RAIDs. The study group will assess the issues and then formulate a strategy for dealing with them. 2. Attendance and Membership Attendance at working group meetings does not count toward minimum attendance requirements for X3T9.2 membership. Working group meetings are open to any person or company to attend and to express their opinion on the subjects being discussed. The following people attended the meeting: RAID Study Group Meeting Attenders Name S Organization Electronic Mail Address ---------------------- - ------------------------- ------------------------- Mr. Norm Harris P Adaptec, Inc. nharris@adaptec.com Mr. Jan V. Dedek P Ancot Corp. Mr. Scott Smyers P Apple Computer smyers.s@applelink.apple. com Mr. Mark Lippitt V Array Technology Corp. Mr. Steve Todd O Data General Corp. steve@genesis24.webo.dg.c om Mr. Charles Monia P Digital Equipment Corp. monia@starch.enet.dec.com Dr. William Ham A Digital Equipment Corp. ham@subsys.enet.dec.com Mr. Ralph Weber A Digital Equipment Corp. weber@star.enet.dec.com Mr. William Dallas A Digital Equipment Corp. dallas@zk3.dec.com Mr. Edward A. Gardner A Digital Equipment Corp. Mr. Dale Robertson V Digital Equipment Corp. Mr. James S. Doucette V Digital Equipment Corp. Mr. Richard Whalen V Digital Equipment Corp. whalen@starch.enet.dec.co m Mr. Matt Giovanetti V Digital Equipment Corp. Mr. Skip Jones P Emulex Corp. Mr. I. Dal Allan P ENDL Mr. Howard Grill O Formation Mr. Jeffrey L. P Hewlett Packard Co. jlw@hplnd48.boi.hp.com Williams Mr. Paul Boulay O Hitachi Computer Prod Amer Mr. Chris Nieves O Hitachi Computer Products c_nieves@hitachi.com Mr. George Penokie P IBM Corp. Mr. John P. Scheible O IBM Corp. Scheible@sjevm5.vnet.ibm. com Mr. Kevin R. Pokorney O Intellistor, Inc. Mr. Ron Roberts A Maxtor Corp. ron_roberts@maxtor.com Mr. Peter Van Beckum V Maxtor Corp. Mr. Raymond C. Yule P Micropolis Corp. Mr. Robbie Shergill P National Semiconductor Mr. John Lohmeyer P NCR Corp. john.lohmeyer@ftcollinsco .ncr.com Mr. Rod DeKoning S NCR Corp. Rod.DeKoning@WichitaKS.NC R.COM Mr. Dennis P. Trupski O Olivetti Mr. James McGrath P Quantum Corp. Mr. Gerald Houlder A Seagate Technology Mr. Gene Milligan A Seagate Technology Mr. Stephen G. Finch P Silicon Systems, Inc. 5723283@mcimail.com Mr. Vit Novak A Sun Microsystems, Inc. Mr. Todd Sprenkle V Tandem Computers sprenkle_todd@tandem.com Mr. Tom Hanan O Western Digital Mr. Roger Nixon O Zitel Corp. 38 People Present Status (S) Key: P - Principal A - Alternate O - Observer L - Liaison V,S - Visitor 3. Approval of Agenda The agenda developed at the meeting was approved. 4. Summary of SCSI Disk Array Items Submitted in the RAID Study Group (93- 002) [Penokie] George reviewed his summary document which merges the inputs received from Ciprico, Digital Equipment, Formation, IBM, and NCR into a common format. Future submissions will not be added to the compilation, but will be distributed directly to X3T9.2. George does not intent to revise this document; the disk array model document (93-003) will be revised to reflect the group's changes. George met resistance from the rest of the group on his idea of not dealing with the "OS issues" in the RAID study group. George contended that these issues are not specific to disk arrays. Others pointed out that the OS issues tend to affect disk arrays more than other SCSI devices. Dal solicited other people to spearhead the effort on the OS issues. 5. SCSI Disk Array Model (93-003) [Penokie] George reviewed his model document. Gene Milligan asked George to define the term "check data" in the glossary. "Behavior" and "group of devices" were deleted in the set definition. Sets are LBA ranges that have the same mapping (characteristics). Dal objected to using the term "LBA" since it is already defined. He wanted some new term (for example, "snook") that this group can re-define. Jim McGrath argued that any one term would cause confusion. He advocated different terms for each array model (for example, "snook A", "snook B", and "snook C"). The discussion red-shifted (increasingly shed more heat than light). George eventually regained control of the meeting. He argued that the array- awareness only occurs at a single layer. Above this layer, the OS is simply talking to mass storage and is unaware that an array is present. Below this layer, there are multiple mass storage devices (that the array manager deals with). Above the array manager, the term relative block address (RBA) was suggested to avoid confusion with LBA. George agreed to revise his document to reflect the group's inputs. 6. Dual Array Controllers (93-011) [Todd] Steve Todd introduced his document which deals with a dual array controller environment in which both array controllers reside on the same SCSI bus and both manage one or more ranks of SCSI drives. Thus, the host system can access the same data through either array controller. Both array controllers may be active at the same time. There needs to be mechanisms to communicate which array controller "owns" the ranks of disk drives. Also, there needs to be methods for the host system to determine that both array controllers actual manage the same data space (as opposed to two separate data spaces). The second page of Steve's document proposes solutions to the problems identified on the first page. 7. Meeting Schedule The next meeting of the RAID Study Group is planned for February 15, 1993 at the Wyndham Southpark in Austin, Texas. The meeting is expected to start at 4:00pm-5:00pm following the X3T9.2 plenary meeting. Plan to stay till 8:00pm. 8. Adjournment The meeting was adjourned at 7:00 p.m. on Monday January 11, 1993. -- John Lohmeyer E-Mail: John.Lohmeyer@FtCollinsCO.NCR.COM NCR Corp. Voice: 719-596-5795 x362 1635 Aeroplaza Dr. Fax: 719-597-8225 Colo Spgs, CO 80916 SCSI BBS: 719-574-0424 300--14400 baud (16800 HST)