I don't think you'd want to issue real R/R "whenever the subject
minidisk begins on real cylinder zero." I say this because VM
systems which host VSE typically have *many* mdisks which begin with
real cylinder 0. Do we really want real reserve/release to occur for
such volumes, especially when you consider that VSE has implemented
its own locking mechanism (the lock file)?
In VSE literature from the '80's, it was said that one should use MWV
only for the lock file itself. Nowadays VM literature says to use
MWV for all shared VSE minidisks. See the following excerpt, quoted
in a posting in the vse listserv, from the z/VM 5.2 Migration Guide:
4.3.1 Reserve/Release Considerations for VSE
z/VM supports virtual reserve/release for minidisks that are not a
full pack. Therefore, the cross-system communication (also called the
"lock file") volume does not have to be defined as a full pack.
MDISK statements for all DASD you want to mount to VSE as shared (in
other words, you want to use the S operand of the IPL ADD statement)
must include the V suffix on the link mode. That is, the link mode
must be MWV. If this is not done, VSE issues MSG 0I23I for the
minidisks that do not have link mode MWV on their MDISK statements.
At 09:02 AM 9/7/2006, you wrote:
I would contend that a REAL R/R should be issued whenever the virtual R/R
is honoured on ANY minidisk associated with a real volume (that supports
real R/R) that's under control of cross-system link (aka XLINK) or
whenever the subject minidisk begins on real cylinder zero.
Tom Cluster
County of Sonoma
Santa Rosa, CA
(707) 565-3384 (Tuesdays and Wednesdays only)
