Each shared memory partition is entitled to some portion of the shared memory pool so that the I/O devices that are assigned to the shared memory partition have access to physical memory during I/O operations. I/O entitled memory is the maximum amount of physical memory (from the shared memory pool) that is guaranteed to be available to a shared memory partition for its I/O devices at any given time. If the minimum amount of memory that I/O devices require for I/O operations does not reside in the shared memory pool for as long as the device needs the memory, the device fails.
The HMC automatically allocates the I/O entitled memory when the logical partition is activated and when you dynamically add or remove an adapter to or from the shared memory partition. However, you can manually set this value. To specify the amount of physical memory to assign to the shared memory partition for its I/O devices, select the Custom I/O entitled memory check box and then specify a value for the I/O entitled memory. You can specify an amount that is greater than the available pool memory. However, when you activate the shared memory partition, the amount of available pool memory must be equal to or greater than the custom I/O entitled memory specified for the shared memory partition.