Apparatus to manage efficient data migration between tiers

摘要

A data storage system having a slow tier and a fast tier maintains hot data on the fast tier by migrating data from the slow tier to reserve space on the fast tier as data becomes hot over time. The system maintains a reserve space table and performs a mass migration of data from the fast tier to the slow tier. Data migration is frequently unidirectional with data migrating from the slow to the fast tier, reducing overhead during normal operation.

主权项

1. A data storage apparatus comprising:
a processor; a first data storage device connected to the processor, configured to store a reserve space table of unmapped data blocks; and a second data storage device connected to the processor, wherein: the first data storage device has a relatively faster access time than the second data storage device; the reserve space table is configured to identify discrete portions of the first data storage device and discrete portions of the second data storage device; and the processor is configured to: transfer data from a discrete portion of the second data storage device to a discrete portion of the first data storage device identified in the reserve space table; after transferring data from the discrete portion, add a location of the discrete portion of the second data storage device to the reserve space table and remove a location of the discrete portion of the first data storage device from the reserve space table; transfer data from a plurality of discrete portions of the first data storage device to a plurality of discrete portions of the second data storage device; after transferring data from the plurality of discrete portions add a plurality of locations, each associated with one of the plurality of discrete portions of the first data storage device to the reserve space table and remove a plurality of locations, each associated with one of the plurality of discrete portions of the second data storage device from the reserve space table.