Patent ID: 8495295

Claim:
A method of operating a mass storage system comprising a storage layer operatively coupled to a plurality of disk drives constituting a storage space, the system configured to enable direct or indirect serving a request directed to any accessible address in the storage space, the method comprising: a. dividing the storage space into an available storage space configured to be available to a client and a spare storage space configured to be unavailable to a client; b. distributing the available space and the spare space over the plurality of disk drives thus giving rise to available space and spare space allocated to each given disk drive; c. detecting underperformance of at least one disk drive among the plurality of disk drives; d. responsive to detecting underperformance, decreasing respective available space allocated to said at least one underperforming disk drive and respectively increasing spare space allocated to said at least one underperforming disk drive thus giving rise to a re-configured allocation of the available space; wherein the amount of increased spare space allocated to said at least one underperforming disk drive is predefined as a certain percentage of respective allocated spare space; and e. transferring the stored data in accordance with said re-configured allocation of the available space.