Managing dedicated memory dynamically

You can add, remove, and move physical memory dynamically to and from running logical partitions that use dedicated memory by using the Hardware Management Console (HMC). This allows you to adjust the physical memory allocated to each logical partition that uses dedicated memory without having to shut down the logical partitions.

When a DPO operation is in progress and you want to dynamically add, remove, or move physical memory to, or from running logical partitions, you must either wait for the DPO operation to complete, or manually stop the DPO operation.

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.