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MPW_WRTCLUSTER is a system parameter that sets the number of pages to be written during one I/O operation from the modified-page list to the page file or a section file. The actual size of the cluster may be limited by the number of pages available for the I/O operation. This parameter can range in value from 16 to 120, in multiples of 8. Each page in the cluster requires 6 bytes of permanently resident memory.

If MPW_WRTCLUSTER is too small, it takes many I/O operations to empty the modified-page list. If MPW_WRTCLUSTER is too large for the speed of the disk that holds the page file, other I/O operations are held up for the modified-page list write.

On Alpha and Integrity servers, the MPW_WRTCLUSTER default value is 64 8192-byte pages; its maximum value is 512 8192-byte pages; and its minimum value is 16 8192-byte pages.

MPW_WRTCLUSTER has the AUTOGEN and GEN attributes.