Automatic Monitoring of Disk Space
For some time now, I have been required to manually monitor
our disk packs mounted STORAGE on a semi-continuous basis.
Inevitably, we get caught with too little space on our disk
packs at the wrong time, with the result that our production
work fails. To combat this, I created a monitor program which
can periodically check the available free space on selected
disk volumes. Volumes which are below a certain threshold
are mounted PRIVATE, while volumes previously mounted
PRIVATE will be mounted STORAGE again if they now exceed the
threshold. Additionally, a minimum number of volumes can
be required to be mounted STORAGE at all times, and that
these "required" volumes have (combined) a minimum amount
of free space between them. If these last two condidtions
are not meet, the program ends with a return code of 4.
Normally, I let the program run all week. It's started at
every IPL, and cancelled at the beginning of our system
backups on the weekend. It would be possible to give the
operator a WTOR (issued via a subtask) to allow him to end
the program "gracefully", but I deemed this unnecessary.
This program could be modified to look at disk packs for
other situations, such as the automatic monitoring of space
on PRIVATE packs. For instance, if a particular pack were to
fall below a certain threshold, the program could issue a
command like this:
/*$VS'SE ''DISK VOLUME PROD01 HAS LESS THAN 50 CYLS'',USER=(X,Y)'
If it was after 5 PM, a WTO could be issued instead, if the
disk volume warrented such action.
R0 EQU 0
R1 EQU 1
R2 EQU 2
R3 EQU 3
R4 EQU 4
R5 EQU 5
R6 EQU 6
R7 EQU 7
R8 EQU 8
R9 EQU 9
R10 EQU 10
R11 EQU 11
R12 EQU 12
R13 EQU 13
R14 EQU 14
R15 EQU 15
1
STORMON CSECT
STM R14,R12,12(R13) SAVE REGISTERS
LR R3,R15 AND ESTABLISH
USING STORMON,R3 ADDRESSABILITY
LA R4,SAVE
ST R4,8(R13)
ST R13,4(R4)
LR R13,R4
*
* GET INPUT PARAMETERS; PARAMETERS MUST BE IN THE FORM:
* PARM='XXXX,NN,NN,NNNN,NNNN'
*
* THESE PARMS CORRESPOND TO
* GENERIC CANDIDATE VOLUME ID
* WAIT TIME IN MINUTES BETWEEN CHK OF PKS
* NUMBER OF REQUIRED STORAGE PACKS
* MINIMUM # OF FREE CYLS ACROSS ALL REQ PACKS
* THRESHOLD LIMIT FOR PACK TO CHANGE FROM
* STORAGE TO PRIVATE STATUS
*
* FOR EXAMPLE,
*
* PARM='STOR,10,03,0300,0100'
*
* WOULD SPECIFY
* CANDIDATE VOLUMES WOULD BEGIN WITH "STOR"
* A 10 MINUTE WAIT TIME
* 3 PACKS ALWAYS REQUIRED TO BE MOUNTED STORAGE
* A MINIMUM OF 300 FREE CYLINDERS ON THOSE 3 PACKS
* A SWITCH TO PRIVATE STATUS FOR OTHER PACKS
* HAVING LESS THAT 100 FREE SYLINDERS ON THEM
* NOTE:
* A PACK WILL BE MOUNTED STORAGE EVEN IF IT HAS LESS THAN THE
* THRESHOLD VALUE, IF IT IS ONE OF THE FIRST N (REQUIRED) PACKS
* AFTER THE PACKS ARE SORTED BY FREE SPACE.
*
* IF THE NUMBER OF REQUIRED PACKS IS GREATER THAT THE NUMBER
* OF PACKS CURRENTLY ONLINE, ALL PACKS WILL BE MOUNTED STORAGE
* AND THE PROGRAM WILL END WITH A NON-ZERO RETURN CODE.
*
* IF THE TOTAL NUMBER OF FREE CYLINDERS IS ON THE FIRST N
* (REQUIRED) PACKS IS LESS THAN THE AMOUNT SPECIFIED, THE
* PROGRAM WILL END WITH A NON-ZERO RETURN CODE.
*
* IF YOU SPECIFY "00" FOR THE WAIT TIME, THE PROGRAM WILL
* CONTINUOUSLY CHECK THE ONLINE CANDIDATE VOLUMES.
*
*
GETPARM L R1,0(R1) GET PARAMETERS ADDRESS
*
MVC STORFLAG(4),2(R1) SAVE GENERIC VOLUME NAME
*
PACK TEMPHOLD(8),7(2,R1) PACK WAIT TIME
CVB R2,TEMPHOLD CHANGE TO BINARY
MH R2,=H'60' CONVERT TIME FROM MIN TO SECONDS
MH R2,=H'100' CONVERT TIME FROM SEC TO HUNDRDS
ST R2,WAITTIME SAVE WAIT TIME
1
*
PACK TEMPHOLD(8),10(2,R1) PACK # OF REQUIRED STOR PKS
CVB R2,TEMPHOLD CHANGE TO BINARY
ST R2,REQSTOR SAVE # OF REQUIRED STOR PKS
*
PACK TEMPHOLD(8),13(4,R1) PACK MINIMUM FREE CYLS
CVB R2,TEMPHOLD CHANGE TO BINARY
ST R2,LOWLIMIT SAVE MINIMUM FREE CYLS
*
MVC THRSHOLD(4),18(R1) SAVE LOWER THRESHOLD FOR SWITCH
* FROM STORAGE TO PRIVATE STATUS
*
* SETUP FOR UCB SCAN OF ONLINE DASD HERE
*
SCAN L R4,CVTPTR GET CVT POINTER (X'10')
USING CVTMAP,R4 ESTABLISH CVT ADDRESSABILITY
MVI DASDDEV,UCB3DACC DEVICE TYPE TO SCAN FOR
OI PARMLIST,X'80' INDICATE LAST PARMLIST FOR UCBSC
XC WORKAREA,WORKAREA CLEAR UCB SCAN WORKAREA
LA R5,STORTABL LOAD TABLE ADDRESS
SR R6,R6 ZERO STORE PACK COUNTER
*
SCANUCBS LA R1,PARMLIST POINT AT PARMLIST
L R15,CVTUCBSC GET UCB SCAN ROUTINE ADDRESS
BALR R14,R15 CALL SCAN ROUTINE
LTR R15,R15 TEST RESULT
*
BNZ SETUP IF RC ^= 0, NO MORE UCBS
L R7,STORUCB GET UCB ADDRESS
USING UCBOB,R7 ESTABLISH ADDRESSABILITY
CLC UCBVOLI(4),STORFLAG IS THIS A PACK A CANDIDATE
BNE SCANUCBS IF NOT, KEEP SCANNING UCBS
MVC 0(4,R5),STORUCB IF SO, SAVE UCB ADDRESS
MVC 4(6,R5),UCBVOLI SAVE VOLUME SERIAL NUMBER
MVC 10(2,R5),UCBCHAN SAVE VOLUME CHANNEL ADDRESS
TM UCBSTAB,X'10' TEST FOR PACK MOUNTED PRIVATE
BO PRIVATE BRANCH IF PACK MOUNTED PRIVATE
TM UCBSTAB,X'08' TEST FOR PACK MOUNTED PUBLIC
BO PUBLIC BRANCH IF PACK IS MOUNTED PUBLIC
MVI 12(R5),C'S' PACK IS MOUNTED STORAGE
B CONTSCAN GO INCREMENT POINTERS
PRIVATE MVI 12(R5),C'P' PACK IS MOUNTED PRIVATE
B CONTSCAN GO INCREMENT POINTERS
PUBLIC MVI 12(R5),C'U' PACK IS MOUNTED PUBLIC
CONTSCAN LA R5,14(R5) POINT PAST INFO JUST SAVED
LA R6,1(R6) INCREMENT STORXX PACK UCB COUNT
B SCANUCBS GO GET NEXT UCB ADDRESS
*
SETUP ST R6,UCBCOUNT SAVE COUNT OF UCBS
L R7,REQSTOR GET # OF REQUIRED STOR PACKS
SR R6,R7 SUB # OF REQ STOR FROM # ONLINE
BNM ENOUGH
1
*
NOTENUF ST R6,OTHERSTR SAVE NUMBER OF (NON-EXISTANT)
* OTHER STORAGE PACKS
MVC REQSTOR(4),UCBCOUNT REDUCE # OF REQUIRED STOR PACKS
* ISSUE HIGHLIGHTED MESSAGE
WTO '# OF STORAGE PACKS IS LESS THAN SPECIFIED',ROUTCDE=1
B OPENRDR OPEN INTRDR AND MOUNT ALL AVAIL
* STOR PACKS STORAGE, THEN QUIT
*
ENOUGH ST R6,OTHERSTR SAVE NUMBER OF OTHER STOR PACKS
*
* GET FREE SPACE AVAILABLE ON CANDIDATE PACKS FOUND IN UCB SCAN
*
GETSPACE LA R4,STORTABL POINT AT STOR PACK TABLE
LA R5,SVC78RES POINT AT SVC 78 RESULT AREA
L R6,UCBCOUNT GET COUNT OF UCBS
SVC78LOP L R0,0(R4) GET UCB ADDRESS
LA R1,0(R5) GET CURRENT RESULT AREA ADDRESS
SVC 78 GO GET FREE SPACE INFO
LA R4,14(R4) POINT TO NEXT STOR TABLE ENTRY
LA R5,30(R5) POINT TO NEXT SVC 78 RES AREA
BCT R6,SVC78LOP GET INFO FOR ALL STOR PACKS
*
L R7,UCBCOUNT GET COUNT OF STOR PACKS
SORT1 LA R4,STORTABL POINT AT STOR PACK TABLE
LA R5,SVC78RES POINT AT SVC 78 RESULT AREA
L R6,UCBCOUNT GET COUNT OF STOR PACKS
S R6,=F'1' DECREMENT FOR INNER LOOP OF SORT
*
SORT2 CLC 6(4,R5),36(R5) COMPARE FREE SPACE
BNL NEXTCOMP BRANCH IF ALREADY IN DEC SEQUEN
MVC TEMPHOLD(30),0(R5) SWITCH ENTRIES: SAVE 1ST ENTRY
MVC 0(30,R5),30(R5) MOVE 2ND TO 1ST
MVC 30(30,R5),TEMPHOLD MOVE 1ST TO 2ND
MVC TEMPHOLD(14),0(R4) SWITCH ENTRIES: SAVE 1ST ENTRY
MVC 0(14,R4),14(R4) MOVE 2ND TO 1ST
MVC 14(14,R4),TEMPHOLD MOVE 1ST TO 2ND
NEXTCOMP R4,14(R4) LA POINT AT NEXT STORPACK ENTRY
LA R5,30(R5) POINT AT NEXT SVC 78 RESLT ENTRY
BCT R6,SORT2 CONTINUE INNER SORT
BCT R7,SORT1 CONTINUE OUTER SORT
*
* OPEN THE INTERNAL READER, MOUNT THE REQUIRED NUMBER OF PACKS STORAGE
* AND MOUNT THE LAST N CANDIDATE VOLUMES STORAGE OR PRIVATE
*
OPENRDR OPEN (INTERRDR,OUTPUT) OPEN INTERNAL READER
*
REQUIRED LA R4,STORTABL GET STOR PACK TABLE ADDRESS
L R5,REQSTOR GET # OF "MUST HAVE" STOR PACKS
LTR R5,R5 ANY VOLUMES REQUIRED?
BZ LASTPAKS IF NOT, GO LOOK AT "REST" OF PKS
CHKREQS CLI 12(R4),C'S' IS PAK CURRENTLY MOUNTED STORAGE
BE NEXTREQS IF SO, GO LOOK AT NEXT PACK
MVI 12(R4),C'S' ELSE, MARK PACK AS STORAGE
BAL R7,MOUNTVOL AND GO ISSUE MOUNT FOR IT
1
NEXTREQS LA R4,14(R4) POINT AT NEXT STOR TABLE ENTRY
BCT R5,CHKREQS CHECK UNTIL # OF REQUIRED PACKS
* IS SATISFIED
LASTPAKS L R5,OTHERSTR GET BALANCE OF STORAGE PACKS
LTR R5,R5 CHECK IF POSITIVE
BP CHKLASTN IF POSITIVE, CHK LAST N PACKS
BZ CLOSERDR IF ZERO, CLOSE THE INTRDR
*
CLOSE (INTERRDR) CLOSE THE INTRDR
B EXITPGM TOO FEW PACKS ONLINE--EXIT PGM
*
CHKLASTN L R5,REQSTOR GET NUM PACKS ALREADY PROCESSED
MH R5,=H'30' MULTIPLY BY SVC 78 RES ENTRY LEN
A R5,=A(SVC78RES) PNT AT SVC 78 RES AREA FOR PK #N
L R6,OTHERSTR GET COUNT OF OTHER STOR PACKS
CHKLN CLC 6(4,R5),THRSHOLD COMAPRE # FREE CYLS TO THRESHOLD
BL MOUNTP IF < THAN THRES, MOUNT PRIVATE
MOUNTS CLI 12(R4),C'S' IS PACK ALREADY MOUNTED STORAGE?
BE NEXTLN IF SO, GO INCREMENT POINTERS
MVI 12(R4),C'S' ELSE SET PACK TO STORAGE
BAL R7,MOUNTVOL AND ISSUE MOUNT COMMAND
B NEXTLN INCREMENT POINTERS
MOUNTP CLI 12(R4),C'P' IS PACK ALREADY MOUNTED PRIVATE?
BE NEXTLN IF SO, GO INCREMENT POINTERS
MVI 12(R4),C'P' ELSE SET PACK TO PRIVATE
BAL R7,MOUNTVOL AND ISSUE MOUNT COMMAND
NEXTLN LA R4,14(R4) POINT AT NEXT STOR PACK ENTRY
LA R5,30(R5) POINT AT NEXT SVC 78 RESLT ENTRY
BCT R6,CHKLN CONTINUE TO CHECK LAST N PACKS
*
CLOSERDR CLOSE (INTERRDR) CLOSE INTERNAL READER
*
* CHECK THE REQUIRED VOLUMES TO INSURE THAT THEY HAVE MORE THAN
* THE SPECIFIED MINIMUM AMOUNT OF FREE SPACE BETWEEN THEM
*
CHKSPACE LA R4,SVC78RES POINT AT STOR PACK TABLE
L R5,REQSTOR GET # OF REQUIRED STORAGE PACKS
SR R6,R6 CLEAR ACCUMULATOR
CHKSLOOP PACK TEMPHOLD(8),6(4,R4) GET NUMBER OF
CVB R7,TEMPHOLD FREE CYLS FOR THIS PACK
AR R6,R7 ADD TO ACCUMULATOR
LA R4,30(R4) POINT AT NEXT SVC 78 RESLT AREA
BCT R5,CHKSLOOP CONTINUE SPACE CHECK LOOP
S R6,LOWLIMIT COMPARE TO MINIMUM ALLOWED VALUE
BM TOOLOW BRANCH IF VALUE IS LESS THAN MIN
STIMER WAIT,BINTVL=WAITTIME ELSE WAIT FOR ONE TIME INTERVAL
B SCAN GO BEGIN PROCESS AGAIN
TOOLOW WTO '# OF FREE CYLS ON REQUIRD PACKS LESS THAN SPECIFIED', X
ROUTCDE=1
EXITPGM L R13,4(R13) GET OLD SAVE AREA
LM R14,R12,12(R13) RESTORE REGISTERS
LA R15,4 SET BAD RETURN CODE
BR R14 EXIT PROGRAM
1
*
* MOUNT VOLUME SUBROUTINE
*
MOUNTVOL LH R8,10(R4) GET CHANNEL ADDRESS
SRL R8,8 GET RID OF LOW BYTE
A R8,=A(CONVTABL) ADD TABLE START ADDRESS
MVC CCU(1),0(R8) MOVE PROPER CHAR INTO 1ST POS
*
LH R8,10(R4) GET CHANNEL ADDRESS
SRL R8,4 GET RID OF LOW NIBBLE
N R8,=F'15' GET RID OF HIGH NIBBLE
A R8,=A(CONVTABL) ADD TABLE START ADDRESS
MVC CCU+1(1),0(R8) MOVE PROPER CHAR INTO 2ND POS
*
LH R8,10(R4) GET CHANNEL ADDRESS
N R8,=F'15' GET RID OF MIDDLE AND HI NIBBLES
A R8,=A(CONVTABL) ADD TABLE START ADDRESS
MVC CCU+2(1),0(R8) MOVE PROPER CHAR INTO 3RD POS
*
MVC VOLSER(6),4(R4) MOVE VOLSER INTO COMMAND
CLI 12(R4),C'S' IS PACK TO BE MOUNTED STOR?
BNE MOUNTPRI IF NOT, GO MOUNT PRIVATE
MOUNTSTR MVC ATTRIBUT(7),=CL7'STORAGE' MOVE ATTRIBUTE TO COMMAND
B ISSUECMD GO ISSUE COMMAND
MOUNTPRI MVC ATTRIBUT(7),=CL7'PRIVATE' MOVE ATTRIBUTE TO COMMAND
ISSUECMD PUT INTERRDR,COMMAND WRITE COMMAND TO INTRDR
BR R7
*
* DATA AREAS
*
INTERRDR DCB DSORG=PS,RECFM=FB,BLKSIZE=80,LRECL=80,MACRF=(PM), ...