Abstract: A hybrid messaging model including a method that sends a first request message from a control process executing on a computer to a plurality of subordinate processes. The first request message directs the subordinate processes to enter a first state. An expected state is set equal to the first state in response to sending the first request message. A status message, including the expected state, is periodically broadcast from the control process to the plurality of subordinate processes. At least one confirmation message is received from each of the subordinate processes confirming that the subordinate process is in the expected state. Each of the confirmation messages is responsive to either the first request message or to the status message. A second request message is sent from the control process to the plurality of subordinate processes in response to receiving at least one confirmation message from each of the subordinate processes.

Abstract: Transparent file system migration including a method that identifies a source physical storage location in a file system that supports simultaneous access by multiple independent processes. A target physical storage location in the file system is identified and its contents are migrated to the target physical storage location. The migrating includes disallowing new allocations to the source physical storage location and copying contents from the source physical storage location to the target physical storage location. A write request to write data to the source physical storage location is received prior to or during the migrating. The write request is serviced contemporaneously with the migrating. Read and write requests directed to the source physical storage location are redirected to the target physical storage location. The redirecting is responsive to the migrating completing. The requests are from the multiple independent processes and include both logical and physical input/outputs.

Abstract: A hybrid messaging model including a method that sends a first request message from a control process executing on a computer to a plurality of subordinate processes. The first request message directs the subordinate processes to enter a first state. An expected state is set equal to the first state in response to sending the first request message. A status message, including the expected state, is periodically broadcast from the control process to the plurality of subordinate processes. At least one confirmation message is received from each of the subordinate processes confirming that the subordinate process is in the expected state. Each of the confirmation messages is responsive to either the first request message or to the status message. A second request message is sent from the control process to the plurality of subordinate processes in response to receiving at least one confirmation message from each of the subordinate processes.

Abstract: Transparent file system migration including a method that identifies a source physical storage location in a file system that supports simultaneous access by multiple independent processes. A target physical storage location in the file system is identified and its contents are migrated to the target physical storage location. The migrating includes disallowing new allocations to the source physical storage location and copying contents from the source physical storage location to the target physical storage location. A write request to write data to the source physical storage location is received prior to or during the migrating. The write request is serviced contemporaneously with the migrating. Read and write requests directed to the source physical storage location are redirected to the target physical storage location. The redirecting is responsive to the migrating completing. The requests are from the multiple independent processes and include both logical and physical input/outputs.