Utilities and Other Interfaces › DASD Reserve Validation Utility › Install the Utility

Install the Utility

The utility requires that a test data set be allocated on the shared DASD device in question. Then, the JCL PROC of the utility needs to be customized and started on all systems that have access to the DASD device being tested. The utility remains active on all systems until 1) it is terminated using a z/OS CANCEL command, 2) it is terminated by replying to its outstanding WTOR, or 3) it detects a reserve failure, issues an error message, then abends with a U0011.

To install the DASD reserve validation facility

1. Allocate a test data set on the shared DASD volume in question. The following is a sample JCL to perform the allocation:

   //ALLOCDS JOB 1,'allocate data set',CLASS=A 
   // * 
   //ALLOC EXEC PGM=IEFBR14 
   //SHARED DD DISP=(NEW,CATLG),DSN=MIM.PROOF.TEST.DATASET 
   // UNIT=xxxx,VOL=SER=XXXXXX,SPACE=(TRK,1)
   

2. Customize the PROCRSV JCL PROC, rename it to RSVTEST, and copy it to an appropriate proclib.
3. Start the RSVTEST JCL PROC on all systems that have access to the DASD device being tested. In a complex having eight systems accessing the same DASD device, the z/OS START commands would be coded as follows:

   On SYSA: START RSVTEST,INDEX=0,CYCLE=02,FORMAT=F (on 1st system) 
   On SYSB: START RSVTEST,INDEX=1,CYCLE=03 (on 2nd system) 
   On SYSC: START RSVTEST,INDEX=2,CYCLE=04 (on 3rd system) 
   On SYSD: START RSVTEST,INDEX=3,CYCLE=05 (on 4th system) 
   On SYSE: START RSVTEST,INDEX=4,CYCLE=06 (on 5th system) 
   On SYSF: START RSVTEST,INDEX=5,CYCLE=07 (o	n 6th system) 
   On SYSG: START RSVTEST,INDEX=6,CYCLE=08 (on 7th system) 
   On SYSH: START RSVTEST,INDEX=7,CYCLE=09 (on 8th system)
   

   Notes:

   • INDEX is the relative system index number having a range of 0-7.
   • CYCLE is the reserve delay interval having a range of 00-99(decimal).You must include the leading 0 if the value is 9 or less. i.e. “09” not “9” This value determines the number of 0.1 second intervals that MIM will wait while reserving the file, and also how long MIM will wait after it has released the file. For example, if CYCLE=05, then MIM will reserve the file for .5 seconds, release the file, wait another .5 seconds, then reserve it again. So, MIM should have a total of approximately 1 reserve per second. The best test results are achieved by staggering this value on each system as shown above.
   • FORMAT has a value of F or N and is used to initialize the test data set. The first utility proc started must specify FORMAT=F; all subsequent systems must specify FORMAT=N.
4. Monitor message traffic on all eight systems for MIMPROOF messages. When the utility is active on each system, a WTOR is issued that can be used to terminate the utility manually. The utility runs indefinitely until you respond to the WTOR of the utility, or a hardware reserve failure is detected. If a reserve failure is detected, then another MIMPROOF error message is issued containing some diagnostic data, and it will abend with a U0011. The utility cannot determine why the failure occurred. It can only tell you that at least two systems were able to gain simultaneous access to the file. This should never occur if normal reserve processing is being properly maintained by the DASD controller microcode. Contact your DASD hardware vendor for assistance in determining root cause.