ibm:vm370-lib:cms:dmsfor.assemble_abs
Table of Contents
DMSFOR Abstract
Statistics
Type ASSEMBLE
Source Lines : 1,748
Fixes Applied : 2
Most Recent Version : Tuesday, December 12, 1978
Last Fix ID : [HRC013DS]
Synopsis
Module
DMSFOR (FORMAT)
Function
TO PHYSICALLY INITIALIZE A DISK SPACE FOR THE CMS
DATA MANAGEMENT ROUTINES. FOR AN EXISTING DISK, IT
MAY IN EFFECT BE CLEARED; A LABEL MODIFIED; RECOMPUTE
THE NUMBER OF CYLINDERS THAT ARE ALLOWED TO BE USED.
Attributes
DISK RESIDENT; SERIALLY REUSABLE.
Operation
INITIALIZATION PHASE
DMSFOR VALIDATES THE PARAMETER LIST. A CHECK IS
MADE TO VERIFY THAT THE SPECIFIED CCU IS VALID (NONZERO)
AND NOT GREATER THAN X'FFF'. FURTHER, THE MODE
IS CHECKED FOR VALIDITY AND A SPECIFICATION OF 'S'
FOR THE SYSTEM DISK WILL, OF COURSE, NOT BE
ALLOWED. THE SPECIFIED DEVICE IS THEN VERIFIED TO
BE A READ/WRITE DASD DEVICE. A CP DIAGNOSE IS
THEN ISSUED TO DETERMINE IF THE DEVICE IS
ATTACHED AND READY AND TO DETERMINE THE ACTUAL
DEVICE TYPE. IF ANY CONDITION IS NOT MET OR THE
DEVICE TYPE IS NOT RECOGNIZABLE AN ERROR CODE AND
SUITABLE MESSAGE IS PRODUCED.
DMSFOR CONTINUES AS DESCRIBED IN THE FOLLOWING
SECTIONS.
REAL FORMAT (FORMAT CCU MODE <NN>)
IF THE DISK IS REALLY TO BE FORMATTED (NONE OF THE
SPECIAL OPTIONS R, OR L WAS SPECIFIED), THE PROCEDURE
USED IS AS FOLLOWS. THE GENERAL DESCRIPTION WILL BE
THAT OF THE PROCEDURE FOLLOWED FOR THE A-DISK;
FORMATTING OF THE OTHER DISKS IS IDENTICAL IN
OPERATION. WHERE THERE ARE DIFFERENCES FOR A
DYNAMICALY CREATED DISK SPACE, THEY ARE NOTED AND
ALSO SUMMARIZED IN A LATER SECTION. A DYNAMICALLY
CREATED DISK SPACE IS CARVED OUT OF A POOL OF
AVAILABLE CYLINDERS BY CP. THE USER HAS A VIRTUAL
MACHINE DIRECTORY ENTRY WHICH SPECIFIES A TEMP DISK
AT ADDRESS 192 IS TO BE NN CYLINDERS. AT LOGON TIME,
CP PRESENTS TO CMS A DISK SPACE AT 192 OF NN
CYLINDERS WITH RELATIVE TRACK 00 00 ZEROED OUT.
THEREFORE, AFTER USING A DYNAMICALLY CREATED DISK
SPACE (HEREAFTER TO BE REFERRED TO AS THE DY- DISK) AND
LOGOUT FROM CP, THE INFORMATION THAT WAS PLACED ON
THAT DISK IS LOST. ALTHOUGH, DURING A TERMINAL
SESSION, THE DISK AND INFORMATION THEREUPON IS KEPT
ALIVE ACROSS THE RE-IPLING OF THE CMS NUCLEUS.
1. TO GUARD AGAINST ACCIDENTAL OR INCORRECT CALL OF
DMSFOR, WHICH CAN CAUSE THE ERADICATION OF
ALL FILES ON A DISK, A MESSAGE IS TYPED ON THE
USER'S TERMINAL BEFORE ANY TABLES ARE CLEARED OR
ANYTHING IS WRITTEN ON TO DISK. THIS MESSAGE
(WITH DISK-MODE AND DEVICE-ADDRESS FILLED IN TO
THEIR CORRECT VALUES) REQUIRES A REPLY OF 'YES'
OR 'NO' BEFORE THE PROGRAM WILL RESUME.
THE USER MUST TYPE IN YES FOR FORMATTING TO BE
UNDERTAKEN. ANY OTHER INPUT AT ALL FROM THE
TERMINAL WILL RESULT IN AN ERROR-CODE 11 BEING
RETURNED, NOTHING AT ALL IN THE NUCON OR ACTIVE
DISK TABLE BEING AFFECTED, AND A MESSAGE
INDICATING THAT FORMAT WILL NOT BE EXECUTED
IS TYPED AT THE VIRTUAL CONSOLE.
FOR THE DY-DISK, DURING CMS INITIALIZATION
THIS ENTIRE STEP IS OMITTED; FORMATTING
PROCEEDS WITH NO MESSAGE TO THE TERMINAL OR
FURTHER INPUT FROM THE USER.
2. DMSCRD IS THEN CALLED TO OBTAIN THE LABEL TYPED
BY THE USER IN RESPONCE TO THE LABEL REQUEST
MESSAGE THAT IS PART OF THE FORMAT PROCEDURE.
THE TYPED-IN LABEL (BLANK-FILLED IF LESS THAN
SIX BYTES, TRUNCATED IF MORE) IS WRITTEN ON THE
FIRST TEN BYTES OF RECORD 3 WHEN THE FORMATTING
IS DONE.
(FOR EXAMPLE, IF THE USER TYPED IN MYDISK, THE
LABEL WOULD BE: VOL1MYDISK). FOR THE DY-DISK, NO
MESSAGE IS GIVEN, NO USER REPLY, AND A LABEL OF
VOL1DYDISK IS ALWAYS USED.
3. AT THIS POINT, DMSALU IS CALLED TO RELEASE AND
CLEAR ALL APPROPRIATE
RESIDENT TABLES FOR THIS DISK, AND THE R/O AND
R/W FLAG-BITS IN THE ADTFLG1 FLAG-BYTE IN THE
ACTIVE DISK TABLE ARE CLEARED.
4. JUST BEFORE FORMATTING STARTS, A MESSAGE IS TYPED,
OF THE FOLLOWING FORM:
FORMATTING CCU DISK'MODE' (2314|3330).
THIS MESSAGE CONFIRMS TO THE USER THAT THE
FORMAT PROGRAM IS FORMATTING THE DESIRED DISK,
AND INDICATES THE DISK TYPE.
FORMATTING OF THE DISK THEN COMMENCES. A 3330
IS FORMATTED BY WRITING 14 800-BYTE RECORDS PER
HEAD, 19 HEADS PER CYLINDER. A 3340 IS FORMATTED
BY WRITING 8 800-BYTE RECORDS PER HEAD, 12 HEADS
PER CYLINDER. A 3350 IS FORMATED BY WRITING 19
800-BYTE RECORDS PER HEAD, 30 HEADS PER CYLINDER.
A 3380 IS FORMATTED WITH 36 800-BYTE RECORDS PER HRC004DS
HEAD AND 15 HEADS PER CYLINDER. HRC004DS
A 2314 OR 2319 IS FORMATTED WITH
15 800-BYTE RECORDS PER TWO HEADS, FOR TEN PAIRS
OF HEADS PER CYLINDER. THE DATA WRITTEN (EXCEPT
FOR THE LABEL) CONSISTS OF BINARY ZEROES. A
READ-AFTER-WRITE CHECK IS INCLUDED IN THE CCW
CHAIN FOR THE DISK, WHERE THE DATA WRITTEN ON
THE DISK IS IMMEDIATELY READ (IN NON-TRANSMIT
MODE) TO CHECK THAT THE FORMATTING WAS
SUCCESSFUL. FOR PURPOSE OF SPEED, THE
READ-AFTER-WRITE CHECK IS NOT PERFORMED ON THE
DY-DISK, AS THE DY-DISK MAY BE FORMATTED ONCE
FOR EACH TERMINAL SESSION, WHILE THE OTHER DISKS
ARE USUALLY FORMATTED ONLY ONCE IN A GREAT
WHILE.
IF ERRORS DO OCCUR, REPEATED EFFORTS TO RECOVER
ARE MADE BY CP AND IF AN ERROR RETURN FROM THE
CP DIAGNOSE IS RECEIVED, THE ERROR IS CONSIDERED
TO BE PERMANENT. A MESSAGE INDICTING THE POINT
AT WHICH FORMATTING WAS TRUNCATED AND AN
ANNOUNCEMENT OF THE ERROR CONDITION IS MADE TO
USER THAT HE MIGHT TAKE THE APPROPRIATE ACTION.
5. FORMATTING OF THE DISK CONCLUDES WHEN THE END OF
DISK IS REACH (DETERMINED BY A UNIT CHECK
COUPLED WITH A SENSE BYTE OF X'81'), OR IF A
SPECIFIED LIMIT BY THE USER IS REACHED (FOR
EXAMPLE, 50 CYLINDERS FOR FORMAT A 50), OR IF A
PERMANENT ERROR OCCURS, WHICHEVER HAPPENS FIRST.
IF THE NUMBER OF CYLINDERS FORMATTED IS ZERO,
THEN DMSFOR EXITS WITH AN ERROR
MESSAGE, AND NO FURTHER ACTION IS TAKEN.
6. IF AT LEAST ONE CYLINDER WAS SUCCESSFULLY
FORMATTED, THEN DMSFOR CONCLUDES AS
FOLLOWS:
A. STORES THE NUMBER OF CYLINDERS ADTCYL IN THE
ACTIVE DISK TABLE.
B. TYPES A MESSAGE INDICATING HOW MANY CYLINDERS
WERE FORMATTED.
C. STORES THE DEVICE DEPENDANT UNIT-TYPE-BYTE
IN THE APPROPRIATE SLOT IN THE NUCON TABLE.
D. OBTAINS A 816-BYTE BLOCK FROM FREE STORAGE,
IF NECESSARY, FOR THE FIRST FST HYPERBLOCK,
CLEARS IT, AND PLACES ITS ADDRESS IN THE
ACTIVE DISK TABLE.
E. OBTAINS A 200-BYTE BLOCK FROM FREE STORAGE,
IF NECESSARY, FOR THE QQMSK TABLE, CLEARS
IT, AND PLACES ITS ADDRESS IN THE ADT
TABLE.
F. OBTAINS FREE STORAGE FOR THE QMSK BIT-MASK
TABLE, THE SIZE DEPENDING ON THE NUMBER OF
CYLINDERS, SETS THE FIRST WORD TO ITS
DEFAULT VALUE OF X'F00000000', CLEARS THE
REMAINDER OF THE TABLE, AND PLACES ITS
ADDRESS IN THE ADT TABLE.
G. INITIALIZES ALL OTHER COUNTS IN THE ADT TABLE
AS NEEDED (ADTNUM, ETC.), AND FLAGS THE
DISK AS LOGGED IN AND READ-WRITE.
H. CALLS DMSAUD TO WRITE THE FINISHED FILE
DIRECTORY ON DISK.
7. FINALLY, DMSFOR RETURNS TO THE CALLER WITH THE
APPROPRIATE ERROR-CODE IN R15.
WAS SUCCESSFUL) IN R15.
CORRECT VALUE OF ADTNUM. THE ACTUAL BITS IN THE
QMSK BIT-MASK ARE THEN COUNTED
RECOMPUTING FORMAT (FORMAT CUU MODE <NN> (R))
RECOMPUTING FORMAT (WITH NO CYLINDER AMOUNT
SPECIFIED), IS USED TO ASCERTAIN THE NUMBER OF
CYLINDERS AND RECOMPUTE THE DISK COUNTS, BUT ALSO HAS
THE CAPABILITY OF REVISING THE DISK COUNT UPWARD IF
ADTNUM IS GREATER THAN IT WAS PREVIOUSLY.
FORMAT MODE RECOMP NN (WHERE NN IS A DECIMAL NUMBER
OF CYLINDERS DESIRED) WORKS LIKE RECOMP WITH NO
OPTIONS, EXCEPT THAT THE NUMBER OF CYLINDERS IS
LIMITED TO THE 'NN' GIVEN BY THE USER.
THE ACTION TAKEN FOR FORMAT RECOMP (WITH OR WITHOUT
OPTIONS) IS AS FOLLOWS:
1. DMSLAD IS CALLED AND THE DISK CHECKED TO MAKE SURE
IT IS ACCESSED IN READ/WRITE MODE.
IN AND IN READ-WRITE FORM.
2. SUCCESSIVE SEEKS TO THE DISK ARE PERFORMED TO
DETERMINE THE ACTUAL NUMBER OF CYLINDERS ON THE
DISK.
3. THE NUMBER OF RECORDS ON DISK ADTNUM IS COMPUTED
FROM THE ACTUAL NUMBER OF CYLINDERS, IF NO
OPTIONS WERE GIVEN. IF "NN" WAS SPECIFIED, THE
"NN" COUNT OR THE ACTUAL NUMBER OF CYLINDERS IS
USED, WHICHEVER IS LESS. THE REVISED DISK COUNTS
ARE THEN COMPUTED. THE ACTUAL BITS IN THE QMSK
BIT-MASK ARE THEN COUNTED TO COMPUTE THE VALUE
OF ADTUSED (NUMBER OF RECORDS IN USE), ADTLEFT
(NUMBER LEFT), AND ADTLAST. ADTLAST IS CLEARED,
AND THE NUMBER OF CYLINDERS ADTCYL IS STORED.
"ADTLAST" (PLUS A SAFETY FACTOR IN THE ADTRES
RESERVE COUNT) IS LESS THAN THE OLD ADTLAST, A
LOSS OF DATA WOULD RESULT; IN THIS CASE, A
WARNING MESSAGE IS GIVEN TO THE USER, THE OLD
DISK COUNTS ARE LEFT INTACT, AND ERROR 13 IS
RETURNED TO THE CALLER. IF THE NEW ADTNUM IS
THE SAME AS THE OLD, FORMATTING TERMINATES
AFTER A CALL TO DMSAUD AND DMSQRY.
DMSAUD IS THEN CALLED TO ENSURE THAT THE
RECOMPUTED COUNTS ARE STORED ON DISK.
FINALLY, DMSQRY IS CALLED TO DISPLAY THE DISK
COUNTS TO THE USER.
4. IF THE TOTAL NUMBER OF RECORDS INDICATED IN ADTNUM
FOR THE DISK TO BE RECOMPUTED IS NOT THE SAME AS
PREVIOUSLY (AND NO DATA-LOSS WILL OCCUR), RECOMP
OBTAINS A NEW QMSK BIK-MASK CORRESPONDS TO THE
NEW DISK COUNTS, MOVES THE OLD QMSK BIT-MASK
THERETO, TRUNCATING OR ZERO FILLING AS
APPROPRIATE, AND GIVES BACK THE OLD BIT-MASK TO
FREE STORAGE. THEN ALL NEW COUNTS ARE STORED IN
THE ACTIVE DISK TABLE
(INCLUDING THE REVISED ADTCYL CYLINDER COUNT),
DMSAUD IS CALLED, AND FINALLY DMSQRY.
RECOMP MAKES IT POSSIBLE TO REVISE DISKS WHENEVER
FEASIBLE, TO LARGER OR SMALLER SIZES, WITHOUT THE
NECESSITY OF DUMPING FILES OUT ON TAPE, FORMATTING
THE DISK, AND LOADING THEM BACK IN AGAIN. THE ONLY
REQUIREMENT, OTHER THAN THOSE DISCUSSED ABOVE, IS
THAT WHEN A DISK IS ENLARGED VIA RECOMP IT WAS
PREVIOUSLY FORMATTED AT SOME TIME TO ITS FULL SIZE.
CMS DISK-LABEL
RECORD 3 (CYLINDER 0, HEAD 0, RECORD 3) OF A CMS DISK
INCLUDES A TEN-BYTE LABEL, CONSISTING OF THE
FOLLOWING:
1. FOUR CHARACTERS: VOLI
2. SIX CHARACTERS: DESIRED LABEL
(BLANK-FILLED IF LESS THAN 6;
TRUNCATED IF MORE THAN 6 CHARACTERS)
3. REMAINING 790 BYTES OF RECORD=00 (BINARY ZEROES)
OPTION TO WRITE A LABEL ON DISK
AS MENTIONED EARLIER, THE OPTION TO FORMAT A
CMS DISK CAUSES THE DISK TO BE FORMATTED INCLUDING A
LABEL ON RECORD 3.
A LABEL CAN ALSO BE ENTERED ON A DISK THAT HAS BEEN
FORMATTED PREVIOUSLY TO CHANGE AN EXISTING LABEL
WITHOUT AFFECTING ANY OTHER INFORMATION ON DISK.
LABEL FORMAT (FORMAT CCU MODE (LABEL))
THE LOGIC PERFORMED FOR A LABEL-ONLY FORMAT IS AS
FOLLOWS:
1. DMSLAD IS CALLED TO MAKE SURE A DISK EXISTS FOR
THE PLIST SPECIFICATION. (OTHER VERIFICATION IS
ACCOMPLISHED AS PART OF THE GENERAL INITIALIZING
PROCESS.) THE DISK MUST, OF COURSE, BE
ATTACHED, READY, AND BE A READ-WRITE DISK, FOR
THE COMMAND TO SUCCEED.
2. DMSDIOR IS CALLED TO READ THE OLD LABEL FROM DISK
INTO AN 800-BYTE I/O BUFFER. (IF DMSDIOR SHOULD
FAIL, A DESCRIPTIVE ERROR MESSAGE IS GIVEN.)
3. A MESSAGE IS TYPED ON THE USER TERMINAL ASKING FOR
A 6-BYTE LABEL TO BE ENTERED.
4. DMSCRD IS CALLED TO OBTAIN THE LABEL TYPED IN BY
THE USER.
5. VOLI (FOUR BYTES) AND THE FIRST SIX BYTES OF THE
ENTERED LABEL
(BLANK-FILLED, IF LESS THAN 6 WERE INPUTTED) ARE
MOVED TO THE FIRST TEN BYTES OF THE 800-BYTE I/O
BUFFER.
6. DMSDIOW IS THEN CALLED TO WRITE THE NEW LABEL BACK
ON THE DISK. (IF DMSDIOW SHOULD FAIL, A
DESCRIPTIVE ERROR MESSAGE IS GIVEN, AND THE
ERROR-CODE FROM DMSDIOW IS RETURNED TO THE
CALLER.
SUMMARY OF DIFFERENCES IN FORMATTING A DYNAMIC-DISK
AS MENTIONED ABOVE, THERE ARE SEVERAL DIFFERENCES IN
THE WAY A DY-DISK IS FORMATTED FROM THE PROCEDURE
USED FOR OTHER READ-WRITE DISK. THESE ARE SUMMARIZED
AS FOLLOWS:
1. A LABEL OF VOL1DYDISK IS AUTOMATICALLY WRITTEN ON
RECORD 3. (SEE NOTE BELOW)
2. THE READ-AFTER-WRITE CHECK IN THE CCW CHAIN TO
FORMAT THE DISK IS OMITTED, IN THE INTERESTS OF
MAKING THE FORMATTING OF A TEMPORARY DISK AS
FAST AS POSSIBLE.
3. THE REQUIREMENT FOR THE USER TO TYPE IN YES BEFORE
FORMATTING BEGINS IS WAIVED.
4. NO INFORMATION MESSAGES ARE TYPED DURING
CMS INITIALIZATION.
APPROPRIATE) IS OMITTED (AS WELL AS THE NORMAL
FORMATTING MESSAGES) IF THE (NOTYPE) PARAMETER
WAS GIVEN.
NOTE: IF DESIRED TO CHANGE THE LABEL ON A DY-DISK
AFTER IT HAS BEEN FORMATTED, THE COMMAND
FORMAT 192 D (LABEL)
CAN BE ISSUED, AND THE REPLACEMENT LABEL WRITTEN.
Calls to Other Routines
DMSLAD, DMSFRE, DMSFRET, DMSDIOR, DMSALU, DMSSTD,
DMSAUD, DMSDIOW, DMSCRD, DMSCRW, DMSERR
CALLED BY:
DMSINT, OR USER FROM TERMINAL
EXTERNAL REFERENCES:
ADTSECT, FVSECT
ibm/vm370-lib/cms/dmsfor.assemble_abs.txt · Last modified: 2023/08/06 13:35 by Site Administrator