Patent ID: 7343467
Filing Date: 2008-03-11
Classification: G06F

Abstract:
1. A method of migrating data from a source logical unit to a target logical unit, the source and target logical units corresponding to different areas of storage on one or more storage systems, the method comprising the steps of: providing a plurality of nodes operational with the one or more storage systems; the plurality of nodes comprises a clustered system, the source logical unit and target logical unit are logical entities utilizing the clustered system to access the corresponding areas of storage; providing by the nodes a LUN-device for access by a client, the LUN-device mapping to the source logical unit; grouping data that are to be copied from the source logical unit to the target logical unit into chunks of data; providing a bit-mask having one bit for each chunk of data; dividing the bit-mask into splices of multiple bits; and performing by each of the two or more of the plurality of nodes the following steps repeatedly until the source logical unit has been fully migrated to the target logical unit: migrating, in parallel by the two or more of the plurality of nodes, the data of the source logical unit to the target logical unit; canceling the migrating at any time by coordinating the cancel request amongst all nodes in the cluster system, preserving the source logical unit and its corresponding LUN-device, and deleting the target logical unit and bit-mask; storing multiple copies of the bit-mask in the clustered system, each copy of the bit-mask having an associated checksum; and if any node of the plurality of nodes fails, checking by a surviving node the checksums to identify a valid copy of the bit-mask.