This counter tracks the number of physical disk read I/Os issued to service page faults, which may combine multiple contiguous pages into a single I/O. Because each I/O carries seek and latency overhead, comparing this counter to the number of pages actually read tells the admin how efficiently the system is clustering page-fault reads into larger transfers. For example, if pages read jumps to 500 but read I/Os only rises to 60, the paging subsystem is successfully clustering reads, cutting down on the number of costly disk seeks.