Patent ID: 8782324

Claim:
In a data storage apparatus having (i) processing circuitry and (ii) a pool of non-volatile storage which stores extents, a method of managing placement of the extents within the pool of non-volatile storage, the method comprising: constructing, by the processing circuitry, an active extent list which identifies active extents stored in the pool of non-volatile storage based on a history of extent activity; based on the active extent list, generating a set of preferred extent-tier pairings for extents of a particular logical unit (LUN) slice that are initially stored on a first tier of the pool of non-volatile storage, the set of preferred extent-tier pairings matching (i) a first extent of the particular LUN slice to the first tier of the pool of non-volatile storage and (ii) a second extent of the particular LUN slice to a second tier of the pool of non-volatile storage; and based on the set of preferred extent-tier pairings, maintaining storage of the first extent of the particular LUN slice on the first tier of the pool of non-volatile storage and relocating storage of the second extent of the particular LUN slice from the first tier of the pool of non-volatile storage to the second tier of the pool of non-volatile storage to distribute storage of the first and second extents of the particular LUN slice across multiple tiers of the pool of non-volatile storage in accordance with the history of extent activity.