Prefetching data units to a cache of a storage system

A non-transitory computer readable medium that stores instructions that once executed by a mass storage system causes the mass storage system to execute the steps of:

• receiving or generating a request to fetch, to a cache memory of the mass storage system, a certain data unit that is currently not stored in the cache memory;
• wherein the certain data unit and additional data units form a certain cluster of data units;
• wherein the certain data unit and the additional data units have similar activity signatures;
• wherein at least two data units of the certain cluster differ from each other by at least one of (a) a file system, (b) a logical volume, and (c) an accessing unit;
• wherein each data unit of the certain cluster is associated with an activity signature that provides a coarse estimation of activity related to the data unit during multiple time periods;
• fetching the certain data unit stored in a mass storage unit;
• and prefetching at least some of the additional data units that are not currently stored in the cache memory,
• wherein the multiple data units comprise a plurality of data units that do not belong to the certain cluster;
• wherein the method comprises clustering the multiple data units to clusters, wherein the clusters comprise the certain cluster and at least one other cluster.

A method for prefetching in a mass storage system, the method comprises:

• generating or receiving activity signatures of a data units;
• clustering the data units to multiple clusters;
• wherein each cluster comprises data units having similar activity signatures;
• wherein at least two data units of a certain cluster of the multiple clusters differ from each other by at least one of (a) a file system, (b) a logical volume, and (c) an accessing unit;
• wherein each data unit of the certain cluster is associated with an activity signature related to the data unit provides a coarse estimation of activity related to the data unit during multiple time periods;
• searching within an activity signature of a data unit of the certain cluster of data units for a repetitive pattern having a repetition cycle;
• determining, based on the repetitive pattern, a next repetition of the repetitive pattern;
• and
• performing a prefetch operation based on the next repetition of the repetitive pattern.