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OpenVMS Galaxy Support  



OpenVMS Galaxy software controls operating system instances through shared memory; it implements a resource-sharing association between instances in multiple soft partitions. Multiple independent operating system instances can run in multiple soft partitions without Galaxy. For additional information about OpenVMS Galaxy concepts, see OpenVMS Galaxy Concepts. To create multiple soft partitions, use the Galaxy procedures as described in Chapters 4 through 10, depending on your hardware.

The configuration tree enables the manipulation of resources up and down the tree within each hard partition. The tree defines a hierarchy of physical connectivity and resource ownership. Hardware resources can be assigned ownership at one of several levels, although resources are allocated and used by an instance. An instance is an operating system running within a soft partition.Software partitions govern system resources. CPUs are used only when owned by a soft partition and manipulated by the instance running there; however, CPUs may be owned by higher levels of the configuration tree –– making them visible and available to all instances equally. If boot ownership is not set before a platform box is powered up, and a CPU module is later added to the system, that CPU is owned by the hardware partition to which it was added, and it is programmatically assignable to any of the soft partitions within that hard partition. (The ES47/ES80/GS1280 does not support hot swap of components.)

As soon as an instance of the operating system boots, all its resources are exclusively owned by the soft partition to which it is assigned: only that instance can manipulate its state characteristics. Consequently, it is important to consider the initial allocation of CPUs at powerup –– even those that do not currently exist –– to provide the best division of resources when they become available.

To create multiple soft partitions within a single hard partition, use standard partitioning procedures, as previously described, to create Galaxy configurations with instances running in these soft partitions. How Memory Is Used illustrates how memory is used in a Galaxy instance. Soft partitions require the OpenVMS minimum for memory.  

Figure 8  How Memory Is Used  
How memory is used

The Galaxy ID is within the hard partition and can span the hard partition. That is, if you have two hard partitions and you run Galaxy in both, each Galaxy will have its own unique Galaxy ID. Keep this in mind when you use network management tools; they will also see two Galaxy environments when two Galaxy IDs exist.

Soft Partitioning in the Configuration Tree illustrates four hard partitions (0, 1, 2, 3), each of which has a unique name such as hp0. Within hard partition 0, a Galaxy is shown that contains two soft partitions, the left-most sp1 and sp0. Other Galaxies exist in each of the other hard partitions, as could multiple independent operating system instances if none of them creates or joins a Galaxy. You can run an operating system instance in any soft partition. There is one Galaxy per community because the shared memory used by the Galaxy is owned by the community. This makes it visible and accessible to all instances in the Galaxy membership. All instances running in soft partitions below the community node are potentially eligible to join the Galaxy there. Member nodes may take advantage of the shared resources controlled by the Galaxy. Although independent instances are still able to assign and migrate CPUs, only members of the Galaxy can take advantage of the benefits of shared memory. There can be only one community per hard partition. 

Figure 9  Soft Partitioning in the Configuration Tree  
Soft partitioning


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