Data migration and migration tool - definitions and characteristics

You can use the following list of basic definitions and characteristics to familiarize yourself with data migration and the migration tool.

• Data migration is the copying of data from one device (the source) to another device (the target) and redirecting the I/O to the new device. A request can be for Point-in-Time replication; in this case, volume redirection of I/O operations to the new device does not take place.
• Data replication is the copying of data from one device (the source) to another device (the target) with no I/O redirection: that is, the source device remains online during the copy.
• A migration or replication is the logical relationship between a source and target device.
• The user initiates and controls all migrations/replications. The user identifies from (source) volumes and to (target) volumes.
• Multiple volume migrations and replications can be established during any one session.
• The migration tool is dynamically started and stopped.
• Applications remain unaware that migration is underway. The data is continuously and fully accessible for read and write activity.
• After replication and synchronization are complete, the takeover of the target device is non-disruptive. For Point-in-Time migration, the pairing is broken, leaving the target device in an offline state, and the data within congruent to a specific point in time.
• The tool supports multiple system shared data environments.
• The tool ensures complete physical data integrity.
• The use of the tool is not restricted to any control unit model type or device type. Except as noted, all devices in the data center can participate in a migration session as required.
• A second Point-in-Time copy can be created on the system simultaneously with the creation of a normal target DASD volume or device. This action can be done by specifying two target volume serial numbers in the TDMF REPLICATE control statement.
• Remote target volume. A volume that is used as the target for a Point-in-Time copy migration, which is not directly accessible by the session’s Master System. TDMF completes the replication by transmitting volume data to a remote Migration session, through TCP/IP.
• No user can be allocated to a target volume during migration.
• A source volume cannot contain an active local page data set or swap data set.
• The source and target volumes must be of the same track geometry.

The indicated characteristics represent the ideal of an open and non-disruptive migration facility. Considering the state of the industry today, IBM believes that TDMF takes the lead in meeting these requirements.