Getting Started with OpenVMS: A Guide for New Users (HP Technologies)

Pages on the modified page list are not written to backing store immediately, but only on certain conditions. These include the modified list exceeding a certain size and the free page list falling below a certain size.

This allows OpenVMS the opportunity to group modified pages together for writing to a pagefile. Writing modified pages in large clusters saves a significant amount of overhead.

OpenVMS also supports multiple page files on separate disks to increase the overall speed of the paging mechanism.