Patent ID: 9575690
Date: 2017-02-21
CPC Classifications: G06F

Claim:
1. A method for auto-tiering in a storage resource pool having a number of storage classes, each with one or more storage devices configured to store a plurality of data blocks, the method comprising: updating sets of block access statistics maintained by a storage manager of a sub-LUN auto-tiering (SLAT) file system in response to performing one or more block-level operations on one or more data blocks of the SLAT file system, the sets of block access statistics comprising read and/or write reference counters that are incremented on each non-sequential access of a corresponding data block of the SLAT file system, the SLAT file system being implemented in a virtual address space mapped by the storage manager to one or more of a plurality of logical block addresses, each corresponding to a data block of a SLAT sub-pool that includes a portion of storage resources of each of at least two storage classes, the one or more data blocks being of a first storage class; determining to promote file data stored in the one or more data blocks when the sets of updated block access statistics indicate greater than a threshold count of the reference counters for the one or more data blocks over an adjustable promotion period; determining to demote the file data when the sets of updated block access statistics indicate less than a threshold count of the reference counters for the one or more data blocks over a demotion period defined as a multiple of the promotion period, moving the file data to data blocks of a second storage class when it is determined to promote the file data; and moving the file data to data blocks of a third storage class when it is determined to demote the file data.