Using the VMPROOF Feature › Using VMPROOF to Simulate Control File I/O

Using VMPROOF to Simulate Control File I/O

For this test, a control file must be allocated on the DASD before you begin. CA MIM can use three supported kinds of control files, and VMPROOF can verify them all. Valid types are MVS, CMS, and CMSFP. VMPROOF needs slightly different information for each type of file, and an example is given for each.

This test functions by writing data to disk, then reading the same data back later, and testing for corruption. A single disk record is used by all systems participating in the test. Each system modifies a different eight-byte field within the record. If serialization works correctly, each system consistently retrieves the same data from the record that it writes, but if serialization fails, one or more systems detects an overlay of its eight-byte area.

This test is most valuable when it is run on multiple systems at the same time, but even running on a single system the test verifies that DASD I/O is working properly, and that RESERVE orders do not cause a unit check.

Once the test begins operation, it continues until an error occurs or until it is manually stopped. The VMPROOF program recognizes two console commands, STATUS and STOP.

• The STATUS command can be issued at any time, and produces a display of the test data. By using this command, you can observe how test data changes while the test is running. Data from all systems is visible, and an asterisk is placed beside the data from the system on which you issue the command. Two full words of data, or eight bytes, are displayed for each system. The first word is a decimal counter, and shows how many times the control file has been written by the corresponding system. The second word is a time stamp.
• The STOP command shows the same information as STATUS, and then terminates the test on the local system. Do not use HX to stop VMPROOF because this can result in leaving a RESERVE in effect on the control file.

You may observe a slight delay between the time you enter a STATUS or STOP command and when it is processed. This is because these commands are processed only when no reserve is held on the control file, and a full write/read cycle has been completed.

The general form of the VMPROOF command is:

VMPROOF vdev
VMPROOF vdev [MVS parm dsn]
 VMPROOF vdev [CMS parm volser]
 VMPROOF vdev [CMSFP parm volser cyl]

MVS, CMS, or CMSFP specifies which type of control file you want to test. Specify other parameters for each type of control file.

Specify values for these parameters:

vdev

Indicates the virtual address of the DASD on which the control file resides.

parm

Specifies a four-character word that sets parameters for the VMPROOF program. The first character is the letter F or N, meaning respectively format or do not format the control file. In this context, format refers to an initialization procedure that VMPROOF performs. It is not the same as the CMS FORMAT command, which must be used to allocate a CMS or CMSFP control file.

The first system to begin VMPROOF or MIMPROOF operations should use F and all others should use N. The next character is a number, 0 through 7. Choose a different number for each system running VMPROOF or MIMPROOF. If you use the same number on two systems, VMPROOF incorrectly reports a RESERVE failure. The last two characters of parm are the time period, in 1/10 second intervals, that VMPROOF waits between alternate reads and writes.

dsn

Specifies the z/OS data set name of the control file.

volser

Specifies the minidisk label of the CMS minidisk that is used for a CMS or CMSFP format control file.

cyl

Specifies the absolute cylinder address, in hex, of the CMS minidisk being used for the CMSFP control file.