| 摘要 |
Data is non-disruptively migrated from a source LUN to a target LUN in an active-active cluster with coordination of a host-based copy sweep with duplicating of ongoing writes of all hosts, using iteration and changed block tracking (CBT). During a first iteration, one host performs the copy sweep, and the locations of new application writes at other hosts are recorded in respective CBT records. In each subsequent iteration, the data blocks of the CBT-recorded writes are copied to the target LUN while the locations of new writes are recorded in new CBT records. A final iteration is done with I/O suspended to completely synchronize the target LUN with the source LUN, and the migration then proceeds to a committed state in which the target LUN is used in place of the source LUN. The one host may use write cloning or CBT recording like the other hosts. |
| 主权项 |
1. A method of migrating data from a source LUN to a target LUN in a data processing system having a cluster of multiple host computers and a storage subsystem containing the source LUN and the target LUN, the data being accessed concurrently by applications of the host computers using an association mechanism in each of the host computers initially associating the data with the source LUN as the location of the data in the system, comprising:
performing a synchronization as iterations of concurrent operations at the host computers, a first iteration including a copy sweep by a first host computer to copy all existing data blocks of the source LUN to the target LUN, the first iteration and each subsequent iteration including at each of second host computers recording the locations of data blocks changed by application writes to the source LUN, the recording employing a respective changed-block record of the respective second host computer, each subsequent iteration also including, for each data block location identified in the changed-block record of each of the second host computers for the preceding iteration, copying the corresponding data blocks of the source LUN to the target LUN; and upon completion of the synchronization, performing a commitment including a final iteration and a transition to operation with the target LUN, the final iteration including, for a final set of recorded locations of data blocks in the changed-block record of each of the second host computers, copying the corresponding data blocks of the source LUN to the target LUN, the transition including at each host computer disabling application access to the source LUN and modifying the association mechanism to newly associate the data with the target LUN as the location of the data in the system. |
