System and method for unbalanced RAID management

1. An information handling system comprising:

a plurality of RAID devices defined on a plurality of physical data storage devices, the plurality of RAID devices being defined in an unbalanced configuration, wherein at least a portion of the RAID devices are not wide-striped across all the physical data storage devices; and

a processing unit, wherein the processing unit is configured to dynamically allocate data to the plurality of RAID devices so as to balance data allocation on the plurality of RAID devices, wherein balancing data comprises:

determining a usage factor for each RAID device, wherein the usage factor is based at least in part on usage of the RAID device, which comprises dividing a usage of the RAID device by a number of disks over which the RAID device is striped;

sorting the plurality of RAID devices based at least in part on the determined usage factors; and

selecting a RAID device for removal based at least in part on the sorting of the plurality of RAID devices.

2. The information handling system of claim 1 , wherein the usage factors are used to sort the plurality of RAID devices on a page pool class free list.

3. The information handling system of claim 1 , wherein the usage factor is further based at least in part on an overlapping disk usage, which comprises a sum of the per RAID device disk usage of each RAID device that is striped across a physical disk.

4. The information handling system of claim 3 , wherein the usage factor comprises a sum of the overlapping disk usages of each physical disk that the RAID device is striped across.

5. The information handling system of claim 1 , wherein the processing unit is further configured to balance data allocation where a RAID device crosses a data storage boundary.

6. The information handling system of claim 1 , wherein the processing unit is further configured to balance data allocation where a physical disk is added to or removed from the information handling system.

7. A method for dynamically balancing the allocation of data among a plurality of physical data storage devices having a plurality of RAID devices defined thereon, the plurality of RAID devices being defined in an unbalanced configuration, wherein at least a portion of the RAID devices are not wide-striped across all the physical data storage devices, the method comprising:

determining a usage factor unique to each RAID device, wherein the usage factor is based at least in part on usage of the RAID device, which comprises dividing a usage of the RAID device by a number of disks over which the RAID device is striped;

sorting the plurality of RAID devices based at least in part on the determined usage factors; and

selecting a RAID device for removal based at least in part on the sorting of the plurality of RAID devices.

8. The method of claim 7 , wherein the usage factor is used to sort the plurality of RAID devices on a page pool class free list.

9. The method of claim 7 , wherein a RAID device with the lowest usage factor is removed.

10. The method of claim 7 , wherein balancing occurs where a RAID device crosses a data storage boundary.

11. A method for allocating space from a RAID device in a storage system comprising a plurality of physical data storage devices having a plurality of RAID devices defined thereon in an unbalanced configuration, wherein at least a portion of the RAID devices are not wide-striped across all the physical data storage devices, the method comprising:

for each RAID device:

calculating an amount of space used on each of the plurality of disks by the RAID device;

calculating a total amount of space used by the RAID device by summing the amount of space used by the RAID device on each of the plurality of disks; and

calculating a usage factor for the RAID device based on the calculated total amount of space and a relative performance score of each of the plurality of disks;

sorting the plurality of RAID devices based on the calculated usage factors; and

selecting a RAID device for removal based at least in part on the sorting of the plurality of RAID devices.

12. The method of claim 11 , wherein at least one of the plurality of disks is of a different type than at least one other of the plurality of disks.

13. The method of claim 11 , wherein at least one of the plurality of disks is of a different size than at least on other of the plurality of disks.

14. The method of claim 11 , further comprising:

adding a disk to the plurality of disks;

defining a new RAID device that comprises the added disk;

sorting the plurality RAID devices and the new RAID device based on a usage factor unique to each such RAID device; and

allocating data from the RAID device selected for removal based on the sort.

15. The method of claim 14 , wherein the new RAID device comprises both the added disk and at least one of the plurality of disks.

16. The method of claim 14 , wherein the new RAID device is grouped into a separate group from the plurality of RAID devices.

17. The information handling system of claim 1 , wherein selecting a RAID device for removal is further based at least in part on size of each RAID device of the plurality of RAID devices.

18. The information handling system of claim 1 , wherein selecting a RAID device for removal is further based at least in part on free page percentage of each RAID device of the plurality of RAID devices.

19. The information handling system of claim 1 , wherein the processing unit is further configured to allocate data from the RAID device selected for removal to at least some of the remaining plurality of RAID devices based on the sort.

20. The method of claim 11 , further comprising allocating data from the RAID device selected for removal to at least some of the remaining plurality of RAID devices based on the sort.