Allocating usable capacity from data storage drives having different capacities

A data storage system comprising:

• processing circuitry and memory coupled to the processing circuitry, the memory storing instructions, wherein the instructions, when executed by the processing circuitry, cause the processing circuitry to:
• order a set of data storage drives in descending order of available capacity;
• allocate virtual RAID groups based on the ordered set of data storage drives by, for each virtual RAID group:
• beginning with a second data storage drive in the ordered set of data storage drives, allocating an individual storage slice from each subsequent data storage drive in the ordered set of data storage drives until a total number of storage slices that is required by each virtual RAID group have been allocated to the virtual RAID group;
• updating the available capacities of the data storage drives to reflect the unavailability of storage slices that were allocated to the virtual RAID group;
• and
• re-ordering the set of data storage drives in descending order of available capacity based on the updated available capacities of the data storage drives.

A computer program product including a non-transitory computer readable medium having instructions stored thereon, wherein the instructions, when executed on processing circuitry, cause the processing circuitry to perform steps including:

• ordering a set of data storage drives in descending order of available capacity;
• allocating virtual RAID groups based on the ordered set of data storage drives by, for each virtual RAID group:
• beginning with a second data storage drive in the ordered set of data storage drives, allocating an individual storage slice from each subsequent data storage drive in the ordered set of data storage drives until a total number of storage slices that is required by each virtual RAID group have been allocated to the virtual RAID group;
• updating the available capacities of the data storage drives to reflect the unavailability of storage slices that were allocated to the virtual RAID group;
• and
• re-ordering the set of data storage drives in descending order of available capacity based on the updated available capacities of the data storage drives.