The present invention relates generally to hierarchical storage management, and more particularly to data migration management in a hierarchical storage management system.
Hierarchical Storage Management (HSM) is a data storage technique that provides efficient and cost-effective data management by utilization of fast, high-cost storage media, such as for primary storage, in addition to slow, low-cost storage media, such as for secondary storage. The primary and secondary storage may be, for example, tiered, layered, or otherwise hierarchically arranged, such as in a high-access speed upper layer and a low-access speed lower layer, respectively, to facilitate data retrieval, read/write operation, and the like. For example, the IBM® TS7700 storage system and the IBM® Spectrum Archive Enterprise Edition HSM system may utilize SSD or HDD data storage devices for primary storage, and tape storage devices for secondary storage. Certain HSM systems use cloud technologies, such as the IBM® TS7700 series tape virtualization product, to enable use of cloud data storage for secondary storage.
A conventional HSM technique may provide an HSM scheme by which frequently accessed data may be stored, for example, in a primary disk storage device arranged in an upper layer of an HSM system, in order to facilitate high availability and access of the data. The frequently accessed data may remain in the upper layer until, for example, an access request frequency of the data falls below a predetermined threshold. For example, where the access request frequency of the data falls below the predetermined threshold, a pre-migration operation may be performed by which the data may be copied, and subsequently, a migration operation may be performed by which the data may be removed for transfer to a lower layer for storage. The data, along with other unfrequently accessed data stored in the lower layer, may be transferred to the upper layer by way of a recall operation. Accordingly, pre-migration, migration, and recall operations may be implemented to provide efficient and high-speed data access for users of the HSM system.