Which command can be used to monitor I/O activity?

cpio is a file archiving and copy utility used for backup and restore operations, not a performance monitoring tool.

alstat is not a standard AIX system monitoring command and has no role in I/O performance analysis.

While iostat does exist on some AIX systems for disk statistics, vmstat is the primary and most broadly applicable command cited for monitoring I/O activity in this context.

The vmstat command on AIX provides a comprehensive view of system activity including disk I/O wait statistics, page-in and page-out rates, and block device throughput. It is widely used to identify I/O bottlenecks by examining fields such as wa (I/O wait) in the CPU column and bi/bo (blocks in/out) in the I/O section.