Patent ID: 6981117

Claim:
A method for transferring data from source storage units to target storage units, wherein the source and target storage units are configured within a computer mass storage system, comprising: processing a data transfer operation to transfer data from source storage blocks in one source storage unit to corresponding target storage blocks in one target storage unit; and for each source storage block, performing: (i) before transferring data from one source storage block to the corresponding target storage block, indicating that the source storage block is in a locked state and transmitting a message to host systems capable of requesting data from the source storage block to invalidate information for the source storage block maintained in the host systems, wherein data in the source storage block in the locked state is not accessible to a host data request, and wherein data in storage blocks that are not in the locked state is accessible to the host data request while the data transfer operation is pending; and (ii) indicating that the source storage block is not in the locked state after transferring the data in the source storage block to the corresponding target storage block.