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VMS Help SET, RMS_DEFAULT, Qualifiers, /CONTENTION_POLICY *Conan The Librarian |
/CONTENTION_POLICY=keyword [/SYSTEM]
Allows you to specify fairness under high contention conditions
for write-shared files at the process or system level. Note that
selecting this option may noticeably increase locking overhead.
This option is disabled by default.
In a mixed cluster environment with high contention for specific
buckets, it is possible for accesses to write-shared files on
nodes using read-mode global bucket locking to dominate access
to a bucket. Nodes without this support might be denied timely
access to the bucket.
Additionally, it is possible to observe comparable behavior on
all OpenVMS versions when dealing with accesses to write-shared
files without global buffers enabled. A similar fairness issue
between lock conversions and new lock requests may be observed in
which the new lock requests may remain ungranted for an extended
period of time. Use the /CONTENTION_POLICY qualifier to specify
fairness under high contention conditions.
The following table lists valid PROCESS keywords (/SYSTEM not
specified):
Keyword Description
NEVER Never use the higher overhead option to improve
fairness for any write-shared files accessed by
this process; minimal overhead.
SOMETIMES Use this option for fairer bucket access (but
higher overhead) to any write-shared files with
global buffers enabled accessed by this process.
ALWAYS Use this option for fairer bucket access (but
higher overhead) to all write-shared files
accessed by this process.
SYSTEM_ Use system setting. Note that this keyword is
DEFAULT disallowed with /SYSTEM.
(default)
The following table lists valid SYSTEM keywords (/SYSTEM also
specified):
Keyword Description
NEVER Never use the higher overhead option to improve
(default) fairness for any write-shared files accessed on
the system; minimal overhead.
SOMETIMES Use this option for fairer bucket access (but
higher overhead) to any write-shared files with
global buffers enabled accessed on the system.
ALWAYS Use this option for fairer bucket access (but
higher overhead) to all write-shared files
accessed on the system.
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