Patent ID: 8639900

Claim:
A data storage system comprising: data storage, wherein data is stored in the form of volumes, at least a plurality of said volumes having freespace, and a grouping of a plurality of volumes comprises a pool; and at least one storage control performing the following: initiating migration of data from a pool to generate additional freespace; subsequent to said migration of data, computing fragmentation of data of said pool; determining the amount of existing freespace of said pool; comparing said amount of existing freespace to a freespace threshold, said freespace threshold related to said computed fragmentation, wherein said freespace threshold (T) is determined in accordance with a formula: ( T )=(total storage capacity of the pool)×(nominal threshold)×{range of 0.5 to 1.5} where the value within said range is based on an index of said computed fragmentation; and if said comparison indicates said amount of freespace is below said threshold, adding spill volumes to said pool; and else, keeping said pool intact without adding spill volumes; and initiating defragmentation of said pool.