SEEK contention analysis
Use SEEK to display contention information for a specified device.
- SEEK
- Displays DASD SEEK contention information for a specified device.
- Type:
- Major
- Format:
-SEEK VOLser(vvvvvv) | DEVice(ccc) INTerval(nn) SAMples(nnn)- -
- An action character. It is required in column 1 on the first execution of the command, and to force re-collection on any subsequent execution.
- VOLser|DEVice
- The volser or device address to be analyzed. It is required whenever the action character is specified in column 1. Volser must be 6 characters long; device can be 3 or 4 characters long.
- INTerval
- Indicates how frequently SEEK analysis will be performed. Interval is optional with a default of 10 ms. Valid values are 5—500 ms.
- SAMples
- Indicates the sampling rate as the number of samples taken per interval. Samples is optional, with a default of 70, and a maximum of 999.
An example of the SEEK command follows:
-SEEK VOL(OMON28) INTERVAL(100)In the preceding example, SEEK analysis would be performed every 100 milliseconds for 70 samples for volume OMON28.
The following figure displays the output from a SEEK major command:
Figure 1. SEEK major command output SEEK VOL(OMON28) INT(10) + Unit=3DC Volser=OMON28 Samples=70 Interval=010 ms Time=08:43:21 + Observed Seeks=20 Low Cyl=83 High Cyl=881 Avg Seek=20 cyls
- DATA
- Displays detailed data set information for one or all seeks.
- Type:
- Minor of SEEK
- Format:
-SEEK VOL(OMON28) INTERVAL(100)XDATA ITEM(nnn | cccccccc | *)- nnn
- The 1-to 3-digit sample number that detailed information is requested for.
- cccccccc
- The 1-to 8-character jobname that detailed SEEK information is requested for.
- *
- Displays detailed data for all observed SEEKs. (default)
- X
- This is optional, and may be used to display extent information for each extent in a data set associated with a displayed SEEK observation. If not specified, the display includes extent information for only the extent within the data set accessed during the observed SEEK.
The following figure displays the output from a DATA detail display for all observed SEEKs:Figure 2. DATA minor command output for all observed SEEKs -SEEK VOL(OMON28) INT(10) + Unit=3DC Volser=OMON28 Samples=70 Interval=010 ms SEEKS=20 Time=08:43:21 DATA ITEM(*) + # Jobname ASID Dataset name Cyl Ext Low Hi + -- -------- ---- -------------------------------------------- --- --- ------- + 3 TESTJOB1 1C PAYROLL.TEST.FILE 853 1 840 879 + 6 PRODJOBA 23 PAYROLL.PROD.FILE 83 3 080 099 + 7 PRODJOBA 23 PAYROLL.PROD.FILE 84 3 080 099 + 8 XYZJOB 15A XYZJOB.DATA 773 4 773 773 + 12 TSOUSERX 76 TSOUSERX.JCL.CNTL 310 2 310 310 + 15 TESTJOB1 1C PAYROLL.TEST.FILE 854 1 840 879 + 19 TSOUSERY 8D TSOUSERY.DUMP.LIST 527 10 520 534 + 21 TSOUSERX 89 TSOUSER.COMMON.CLIST 880 1 880 884 + 28 TESTJOB1 1C PAYROLL.TEST.FILE 855 1 840 879 + 32 ABCJOB 143 ABCJOB.DATA 395 1 394 396 + 35 TSOUSERX 76 TSOUSER.COMMON.CLIST 881 1 880 884 + 41 PRODJOBA 23 PAYROLL.PROD.FILE 90 3 080 099 + 42 TSOUSERY 8D TSOUSERY.DUMP.LIST 528 10 520 534 + 45 TESTJOB1 1C PAYROLL.TEST.FILE 859 1 840 879 + 49 TSOUSERX 76 TSOUSERX.JCL.CNTL 310 2 310 310 + 53 TSOUSERY 8D TSOUSER.COMMON.CLIST 881 1 880 884 + 56 TSOUSERY 8D TSOUSERY.DUMP.LIST 529 10 520 524 + 61 TSOUSERZ A7 TSOUSERZ.MISC.LOG 195 1 195 195 + 62 XYZJOB 15A XYZJOB.DATA 773 4 773 773 + 63 PRODJOBA 23 PAYROLL.TEST.FILE 853 1 840 879
SDAT is a synonym of the DATA minor of SEEK. It can be used when the DATA minor has been secured for the PEEK command, making it unavailable.
- PLOT
- Graphically displays SEEK contention for a specified device.
- Type:
- Minor of SEEK
- Format:
SEEK VOL(OMON28) INTERVAL(100)PLOT
The following figure shows the output from a PLOT minor command. The Observed Seeks are plotted by cylinder number. The accessed cylinder is indicated with an asterisk (*) in the graph, along with the direction and distance the device head moved in relation to the previous Seek that was observed during sampling.
Figure 3. PLOT minor command output SEEK VOL(OMON28) INT(10) + Unit=3DC Volser=OMON28 Samples=70 Interval=10 ms Time=08:43:21 + Observed Seeks=20 Low Cyl=83 High Cyl=881 Avg Seek=20 cyls PLOT + # Jobname Cyl 0----100----200----300----400----500----600----700----800-+ + --- -------- ----+----------------------------------------------------------+ + 3 TESTJOB1 853| * | + 6 PRODJOBA 83| *<-------------------------------------------------- | + 7 PRODJOBA 84| * | + 8 XYZJOB 773| ----------------------------------------------->* | + 12 TSOUSERX 310| *<------------------------------- | + 15 TESTJOB1 854| ---------------------------------->* | + 19 TSOUSERY 527| *<--------------------- | + 21 TSOUSERX 880| ---------------------->*| + 28 TESTJOB1 855| *<| + 32 ABCJOB 395| *<----------------------------- | + 35 TSOUSERX 881| ------------------------------>*| + 41 PRODJOBA 85| *<---------------------------------------------------| + 42 TSOUSERY 528| ---------------------------->* | + 45 TESTJOB1 859| --------------------->* | + 49 TSOUSERX 310| *<---------------------------------- | + 53 TSOUSERY 881| ----------------------------------->*| + 56 TSOUSERY 529| *<----------------------| + 61 TSOUSERZ 195| *<--------------------- | + 62 XYZJOB 773| ---------------------------------------->* | + 63 PRODJOBA 853| -->* | - WSIZ nnn
- Controls the size of the work area used for the DATA minor command
of SEEK
- Type:
- Minor of SEEK
The variable nnn is the size of the work area in kilobytes.