Using the VMPROOF Feature › VMPROOF Notes

VMPROOF Notes

The information contained in this section provides some additional considerations when using VMPROOF. Please note the following:

• VMPROOF cannot find some configuration problems. A common one is specifying multiple MDISK statements for the same full pack minidisk. This subverts correct operation of virtual reserve/release (VRR). For VRR to work, there must be a single MDISK specification using mode MWV and all other references to the same full pack must link to the MDISK using mode MW.
• When z/OS or z/VM runs under z/VM, the guest definition at the first level can cause problems that are hard to find at the second level. For example, if a full pack minidisk is defined as read/only (R/O) at the first level, but read/write (R/W) at the second level, second level applications will see the disk as R/W. In this case, MIMPROOF or VMPROOF running at the second level will fail when it attempts to write.
• VMPROOF does not check for the SHARED setting in z/VM systems. Even for a full pack minidisk, z/VM will not forward RESERVE and RELEASE orders to the hardware unless SHARED is set on. You can check this setting yourself by using the QUERY rdev command from any class B user.
• Never run two or more applications that might issue RESERVE to different minidisks on the same real pack. If you allow this to occur, the status of RESERVE on the real pack becomes unpredictable. Fortunately, not many applications issue reserves to a CMS minidisk. It never happens in CMS, for example.
• VMPROOF is compatible with MIMPROOF. You can run VMPROOF on z/VM and MIMPROOF on z/OS at the same time and sharing the same control file to test for correct operation. MIMPROOF cannot access CMS or CMSFP control files, however. MIMPROOF is distributed with CA MIM for z/OS and documented with that product.
• If VMPROOF detects corrupted data, it issues a "RESERVE ERROR DETECTED" message, dumps memory, and stops running with return code 24. The dump will be sent to the reader of the user running VMPROOF.
• VMPROOF stops running when you issue a STOP command or when it detects corrupted data. If VMPROOF is running on two or more user IDs, either on the same system or on different systems, stopping one copy of VMPROOF does not affect the status of the others. Each must be stopped independently of the other.