Adaptive Data Block Placement Based on Deterministic Zones (AdaptiveZ)

The deterministic block distribution method proposed for RAID systems (known as striping) has been a traditional solution for achieving high performance, increased capacity and redundancy all the while allowing the system to be managed as if it were a single device. However, this distribution method requires one to completely change the data layout when adding new storage subsystems, which is a drawback for current applications This paper presents AdaptiveZ, an adaptive block placement method based on deterministic zones, which grows dynamically zone-by-zone according to capacity demands. When adapting new storage subsystems, it changes only a fraction of the data layout while preserving a simple management of data due to deterministic placement. AdaptiveZ uses both a mechanism focused on reducing the overhead suffered during the upgrade as well as a heterogeneous data layout for taking advantage of disks with higher capabilities. The evaluation reveals that AdaptiveZ only needs to move a fraction of data blocks to adapt new storage subsystems while delivering an improved performance and a balanced load. The migration scheme used by this approach produces a low overhead within an acceptable time. Finally, it keeps the complexity of the data management at an acceptable level.