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Managing shared memory dynamically

You can dynamically add and remove logical memory and I/O entitled memory to and from a logical partition that uses shared memory (hereafter referred to as a shared memory partition) using the Hardware Management Console (HMC).

Dynamic memory changes on IBM® i logical partitions affect the base memory pool of the logical partitions (*BASE pool). Private memory pools or shared memory pools are not affected. Dynamic memory changes cannot cause the amount of memory in the base pool to fall below the minimum amount of memory required in the base pool (as determined by the base storage minimum size (QBASPOOL) system value). If a dynamic memory change would cause the base pool to fall below this amount, the system releases excess memory pages only after keeping the minimum amount of memory required in the base pool.

To prevent any data loss during dynamic memory movement, the system first writes any data from memory pages to disk before making the memory pages available to another logical partition. Depending on the amount of memory you have requested to move, this might take some time.

Memory in each logical partition operates within its assigned minimum and maximum values. The full amount of memory that you assign to a logical partition might not be available for the logical partition to use. Static memory overhead that is required to support the assigned maximum memory affects the reserved or hidden memory amount. This static memory overhead also influences the minimum memory size of a logical partition.

Note: If resources are moved dynamically, the configuration change is temporary and is not reflected in the partition profile. This means that all configuration changes will be lost the next time the partition profile is activated. If you want to save your new logical partition configuration, either change the partition profile or save the logical partition configuration to a new partition profile.

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Last updated: Fri, Oct 30, 2009