Compression-aware data storage tiering

#This invention relates generally to computer storage, and specifically to using file compressibility as a factor for data storage tiering.

#Data storage tiering (also referred to herein as data tiering) is a technique used to improve performance in storage systems comprising multiple tiers of storage devices. In data tiering, the storage devices can be assigned to different tiers based on performance of the storage devices (e.g., faster storage devices can be assigned to a first tier and slower devices can be assigned to a second tier).

#Typically, frequently used data is migrated to tiers comprising faster storage devices, and infrequently used data is migrated to tiers comprising slower storage devices. Examples of storage devices for faster storage tiers include solid state disks (SSDs), faster (e.g., 15,000 revolutions per minute) rotating disks such as Serial Attached Small Computer System Interface (SAS) and Fibre Channel (FC) drives, and outer tracks of a rotating disk (On a rotating disk, the outer tracks of the disk typically access data faster than the inner tracks of the disk.) Examples of storage devices for slower storage tiers include slower (e.g., 7,500 revolutions per minute) rotating disks such as SATA drives, and the inner tracks of rotating disks.

#The disclosure is herein described, by way of example only, with reference to the accompanying drawings, wherein:

#FIG. 1 is a schematic pictorial illustration of a system configured to perform compression-aware data storage tiering, in accordance with an embodiment of the present invention; and

#FIG. 2 is a flow diagram that schematically illustrates a method of performing compression-aware data storage tiering, in accordance with an embodiment of the present invention.

#Data compression is a technique used to reduce the space required to store data files on storage devices. Data compression can help reduce the consumption of expensive resources, such as disk space (on devices such as solid state disks and rotating disks) and input/output (I/O) bandwidth. The design of data compression schemes can involve trade-offs among various factors, including the degree of compression, and the computational resources required to compress and uncompress the data.

#In some instances (especially for files that can be compressed to a small fraction of their original size), data compression can increase the I/O performance of a storage device. The increased performance is due to the fact that the time required to retrieve uncompressed data from a storage device is typically greater than the time required to retrieve and uncompress compressed data. Likewise, the time required to store uncompressed data to a storage device is typically greater than the time required to compress and store the data.

#Embodiments of the present invention provide methods and systems for including the compressibility of data as a factor when implementing data storage tiering in a storage system. In some embodiments, a priority score is calculated for each file in the storage system, and each of the storage tiers is assigned a respective range of priority scores. Based on their respective calculated priority scores, the files can be migrated (if necessary) to the appropriate storage tier.