Technical data

System Management Features
4.9 OpenVMS Cluster Systems
Migration support is a superset of the Rolling Upgrade support provided in
earlier releases of OpenVMS and is available for mixes that are not warranted.
Migration support means that Compaq has qualified the versions for use together
in configurations that are migrating in a staged fashion to a newer version of
OpenVMS VAX or of OpenVMS Alpha. Problem reports submitted against these
configurations will be answered by Compaq. However, in exceptional cases,
Compaq may request that you move to a warranted configuration as part of
answering the problem.
Compaq supports only two versions of OpenVMS running in a cluster at the
same time, regardless of architecture. Migration support helps customers move to
warranted OpenVMS Cluster version mixes with minimal impact on their cluster
environments.
Table 4–2 shows the level of support provided for all possible version pairings.
Table 4–2 OpenVMS Cluster Warranted and Migration Support
Alpha/VAX V7.3
Alpha V7.2–xxx/
VAX V7.2 Alpha/VAX V7.1
Alpha/VAX V7.3 WARRANTED Migration Migration
Alpha V7.2–xxx/
VAX V7.2
Migration WARRANTED Migration
Alpha/VAX V7.1 Migration Migration WARRANTED
In a mixed-version cluster with OpenVMS Version 7.3, you must install remedial
kits on earlier versions of OpenVMS. For OpenVMS Version 7.3, two new
features, XFC and Volume Shadowing minicopy, cannot be run on any node in a
mixed version cluster unless all nodes running earlier versions of OpenVMS have
installed the required remedial kit or upgrade. Remedial kits are available now
for XFC. An upgrade for systems running OpenVMS Version 7.2-xx that supports
minicopy will be made available soon after the release of OpenVMS Version 7.3.
For a complete list of required remedial kits, refer to the OpenVMS Version 7.3
Release Notes.
4.10 OpenVMS SMP Performance Improvements (Alpha)
OpenVMS Alpha Version 7.3 contains software changes that improve SMP
scaling. Designed for applications running on the new AlphaServer GS-series
systems, many of these improvements will benefit all customer applications. The
OpenVMS SMP performance improvements in Version 7.3 include the following:
• Improved MUTEX Acquisition
Mutexes are used for synchronization of numerous events on OpenVMS.
The most common use of a mutex is for synchronization of the logical names
database and I/O base. In releases prior to OpenVMS Alpha Version 7.3,
the manipulation of a mutex was completed with the SCHED spinlock held.
Because the SCHED spinlock is a heavily used spinlock with high contention
on large SMP systems and only a single CPU could manipulate a mutex,
bottlenecks often occurred.
OpenVMS Alpha Version 7.3 changes the way mutexes are manipulated. The
mutex itself is now manipulated with atomic instructions. Thus multiple
CPUs manipulate different mutexes in parallel. In most cases, the need to
acquire the SCHED spinlock has been avoided. In cases where a process
4–12 System Management Features