US Patent 9229656 Managing settings and queries in host-based data migration

An improved technique migrating data from a source LUN (logical unit) to a target LUN manages control I/O's in a manner that depends on the current state of data migration and on whether the control I/O's specify that reservation information for a LUN is to be set or queried. Control I/O's specifying reservation settings during the different states of migration are treated the same way as data WRITEs during those respective states, and control I/O's specifying reservation queries during different migration states are treated the same way as data READs during those respective states.