Determining an effective capacity of a drive extent pool generated from one or more drive groups in an array of storage drives of a data storage system that uses mapped RAID (redundant array of independent disks) technology

• US 10,552,078 B2
• Filed: 02/05/2018
• Issued: 02/04/2020
• Est. Priority Date: 01/31/2018
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Gong, Shaoqin, Gao, Jian, Gao, Hongpo, Han, Geng, Dong, Jibing, Kang, Jamin
• Primary Examiner(s): Ko, Chae M
• Application Number:
  US15/888,434
• Publication Number:
  US 20190235781A1
• Time in Patent Office: 729 Days
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 2201/805 Real-time
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

Technology for determining an effective capacity of a drive extent pool that is generated from at least one group of storage drives. A sub-group of storage drives having relatively higher physical capacities is selected from the group. The number of storage drives in the sub-group is equal to a total number of drive extents indicated by each entry in a RAID mapping table. Each storage drive in the sub-group is assigned an individual effective capacity equal to an individual physical capacity of a storage drive in the sub-group having the smallest individual physical capacity. Each storage drive in the group not contained in the sub-group is assigned an individual effective capacity equal to its own physical capacity. An effective capacity of the drive extent pool is set to a sum of the all the individual effective capacities assigned to the storage drives in the group of storage drives.

Claims

1. A method of providing RAID (Redundant Array of Independent Disks) data protection for at least one storage object in a data storage system, wherein the data storage system includes a storage processor and at least one group of storage drives communicably coupled to the storage processor, the method comprising:

generating a drive extent pool from the at least one group of storage drives communicably coupled to the storage processor, wherein the drive extent pool indicates a plurality of drive extents located in the at least one group of storage drives, wherein each drive extent indicated by the drive extent pool comprises a contiguous region of non-volatile data storage located in one of the storage drives contained in the at least one group of storage drives, and wherein each drive extent has a size equal to a predetermined drive extent size;

generating a RAID mapping table, wherein the RAID mapping table contains a plurality of RAID extent entries, wherein each RAID extent entry indicates a unique plurality of drive extents that are allocated from the drive extent pool to the RAID extent entry and that are used to persistently store host data written to a portion of an address space of the storage object corresponding to the RAID extent entry, and wherein each RAID extent entry indicates the same total number of drive extents; and

determining an effective capacity of the drive extent pool at least in part by;

i) generating a minimum drive count that is equal to the total number of drive extents indicated by each RAID extent entry plus one,

ii) selecting a sub-group of storage drives from the group of storage drives, wherein the selected sub-group contains storage drives in the group of storage drives having individual physical capacities that are not less than the physical capacity of any storage drive not contained in the selected sub-group, and wherein a total number of storage drives contained in the selected sub-group is equal to the minimum drive count;

iii) assigning an individual effective capacity to each one of the storage drives contained in the selected sub-group, wherein the individual effective capacity assigned to each one of the storage drives contained in the selected sub-group is equal to an individual physical capacity of a storage drive contained in the selected sub-group that has a smallest individual physical capacity of any storage drive contained in the selected sub-group,

iv) assigning an individual effective capacity to each one of the storage drives in the group of storage drives that is not contained in the selected sub-group, wherein the individual effective capacity assigned to each one of the storage drives in the group of storage drives that is not contained in the selected sub-group is equal to that to the physical capacity of that storage drive,

v) generating a total effective capacity of the group of storage drives that is equal to a sum of the all the individual effective capacities assigned to the storage drives in the group of storage drives, and

vi) setting the effective capacity of the drive extent pool to the total effective capacity of the group of storage drives.

2. The method of claim 1, wherein selecting the sub-group of storage drives from the group of storage drives further comprises:

creating a sorted drive list representing each of the individual storage drives in the group of storage drives, wherein the sorted drive list is sorted in descending order of storage drive physical capacity, such that storage drives in the group of storage drives with higher individual physical capacities are represented closer to a top of the sorted drive list; and

selecting the sub-group of storage drives using the sorted drive list, wherein the storage drives contained in the selected sub-group are represented towards the top of the sorted drive list.

3. The method of claim 2, wherein the at least one group of storage drives comprises a plurality of groups of storage drives;

and

wherein setting the effective capacity of the drive extent pool to the total effective capacity of the group of storage drives further comprises i) generating a total effective capacity of each group of storage drives in the plurality of groups of storage drives, ii) generating a sum of the total effective capacities of the plurality of groups of storage drives, and iii) setting the effective capacity of the drive extent pool to the sum of the total effective capacities of the plurality of groups of storage drives.

4. The method of claim 3, further comprising:

detecting a change in a total number of storage drives communicably coupled to the storage processor; and

wherein determining the effective capacity of the drive extent pool is performed in response to detecting the change in the total number of storage drives communicably coupled to the storage processor.

5. The method of claim 4, wherein detecting the change in the total number of storage drives communicably coupled to the storage processor comprises detecting that at least one new storage drive has been added to the storage drives communicably coupled to the storage processor, such that the total number of storage drives communicably coupled to the storage processor is increased.

6. The method of claim 4, wherein detecting the change in the total number of storage drives communicably coupled to the storage processor comprises detecting that at least one storage drive has been removed from the storage drives communicably coupled to the storage processor, such that the total number of storage drives communicably coupled to the storage processor is decreased.

7. The method of claim 3, further comprising using the effective capacity of the drive extent pool to set a size of the storage object, such that the size of the storage object is set to a value that is less than the effective capacity for the drive extent pool.

8. The method of claim 3, wherein the plurality of groups of storage drives comprises a plurality of partnership groups including at least a first partnership group and a second partnership group;

wherein a plurality of unallocated drive extents located in storage drives contained in the first partnership group are available as free drive extents to be allocated, in response to detecting a failure of a storage drive contained in the first partnership group, to replace drive extents located in the failed storage drive contained in the first partnership group; and

wherein a plurality of unallocated drive extents located in storage drives contained in the second partnership group are available as free drive extents to be allocated, in response to detecting a failure of a storage drive contained in the second partnership group, to replace drive extents located in the failed storage drive contained in the second partnership group.

9. The method of claim 8, wherein drive extents are allocated to RAID extent entries in the RAID mapping table such that no two drive extents indicated by any single RAID extent entry are located on the same storage drive.

10. A data storage system that provides RAID (Redundant Array of Independent Disks) data protection for at least one storage object, comprising:

at least one storage processor including processing circuitry and a memory;

at least one group of storage drives communicably coupled to the storage processor; and

wherein the storage processor is configured and arranged to;

generate a drive extent pool from the at least one group of storage drives communicably coupled to the storage processor, wherein the drive extent pool indicates a plurality of drive extents located in the at least one group of storage drives, wherein each drive extent indicated by the drive extent pool comprises a contiguous region of non-volatile data storage located in one of the storage drives contained in the at least one group of storage drives, and wherein each drive extent has a size equal to a predetermined drive extent size;

generate a RAID mapping table, wherein the RAID mapping table contains a plurality of RAID extent entries, wherein each RAID extent entry indicates a unique plurality of drive extents that are allocated from the drive extent pool to the RAID extent entry and that are used to persistently store host data written to a portion of an address space of the storage object corresponding to the RAID extent entry, and wherein each RAID extent entry indicates the same total number of drive extents; and

Wherein to determine an effective capacity of the drive extent pool the storage processor is configured and arranged to;

i) generate a minimum drive count that is equal to the total number of drive extents indicated by each RAID extent entry plus one,

ii) select a sub-group of storage drives from the group of storage drives, wherein the selected sub-group contains storage drives in the group of storage drives having individual physical capacities that are not less than the physical capacity of any storage drive not contained in the selected sub-group, and wherein a total number of storage drives contained in the selected sub-group is equal to the minimum drive count;

iii) assign an individual effective capacity to each one of the storage drives contained in the selected sub-group, wherein the individual effective capacity assigned to each one of the storage drives contained in the selected sub-group is equal to an individual physical capacity of a storage drive contained in the selected sub-group that has a smallest individual physical capacity of any storage drive contained in the selected sub-group,

iv) assign an individual effective capacity to each one of the storage drives in the group of storage drives that is not contained in the selected sub-group, wherein the individual effective capacity assigned to each one of the storage drives in the group of storage drives that is not contained in the selected sub-group is equal to that to the physical capacity of that storage drive,

v) generate a total effective capacity of the group of storage drives that is equal to a sum of the all the individual effective capacities assigned to the storage drives in the group of storage drives, and

vi) set the effective capacity of the drive extent pool to the total effective capacity of the group of storage drives.

11. The data storage system of claim 10, wherein to select the sub-group of storage drives from the group of storage drives the storage processor is configured and arranged to:

create a sorted drive list representing each of the individual storage drives in the group of storage drives, wherein the sorted drive list is sorted in descending order of storage drive physical capacity, such that storage drives in the group of storage drives with higher individual physical capacities are represented closer to a top of the sorted drive list; and

select the sub-group of storage drives using the sorted drive list, wherein the storage drives contained in the selected sub-group are represented towards the top of the sorted drive list.

12. The data storage system of claim 11, wherein the at least one group of storage drives comprises a plurality of groups of storage drives;

and

wherein to set the effective capacity of the drive extent pool to the total effective capacity of the group of storage drives the storage processor is configured and arranged to i) generate a total effective capacity of each group of storage drives in the plurality of groups of storage drives, ii) generate a sum of the total effective capacities of the plurality of groups of storage drives, and iii) set the effective capacity of the drive extent pool to the sum of the total effective capacities of the plurality of groups of storage drives.

13. The data storage system of claim 12, wherein the storage processor is further configured and arranged to:

detect a change in a total number of storage drives communicably coupled to the storage processor; and

determine the effective capacity for the drive extent pool in response to detection of the change in the total number of storage drives communicably coupled to the storage processor.

14. The data storage system of claim 13, wherein to detect the change in the total number of storage drives communicably coupled to the storage processor the storage processor is configured and arranged to detect that at least one new storage drive has been added to the storage drives communicably coupled to the storage processor, such that the total number of storage drives communicably coupled to the storage processor is increased.

15. The data storage system of claim 13, wherein to detect the change in the total number of storage drives communicably coupled to the storage processor the storage processor is configured and arranged to detect that at least one storage drive has been removed from the storage drives communicably coupled to the storage processor, such that the total number of storage drives communicably coupled to the storage processor is decreased.

16. The data storage system of claim 12, wherein the storage processor is further configured and arranged to use the effective capacity of the drive extent pool to set a size of the storage object, such that the size of the storage object is set to a value that is less than the effective capacity of the drive extent pool.

17. The data storage system of claim 12, wherein the plurality of groups of storage drives comprises a plurality of partnership groups including at least a first partnership group and a second partnership group;

wherein a plurality of unallocated drive extents located in storage drives contained in the first partnership group are available as free drive extents to be allocated, in response to detecting a failure of a storage drive contained in the first partnership group, to replace drive extents located in the failed storage drive contained in the first partnership group; and

wherein a plurality of unallocated drive extents located in storage drives contained in the second partnership group are available as free drive extents to be allocated, in response to detecting a failure of a storage drive contained in the second partnership group, to replace drive extents located in the failed storage drive contained in the second partnership group.

18. The data storage system of claim 17, wherein drive extents are allocated to RAID extent entries in the RAID mapping table such that no two drive extents indicated by any single RAID extent entry are located on the same storage drive.

19. A non-transitory computer readable medium for providing RAID (Redundant Array of Independent Disks) data protection for at least one storage object, comprising instructions stored thereon, that when executed on processing circuitry in a storage processor, perform the steps of:

generating a drive extent pool from the at least one group of storage drives communicably coupled to the storage processor, wherein the drive extent pool indicates a plurality of drive extents located in the at least one group of storage drives, wherein each drive extent indicated by the drive extent pool comprises a contiguous region of non-volatile data storage located in one of the storage drives contained in the at least one group of storage drives, and wherein each drive extent has a size equal to a predetermined drive extent size;

generating a RAID mapping table, wherein the RAID mapping table contains a plurality of RAID extent entries, wherein each RAID extent entry indicates a unique plurality of drive extents that are allocated from the drive extent pool to the RAID extent entry and that are used to persistently store host data written to a portion of an address space of the storage object corresponding to the RAID extent entry, and wherein each RAID extent entry indicates the same total number of drive extents; and

determining an effective capacity of the drive extent pool at least in part by;

i) generating a minimum drive count that is equal to the total number of drive extents indicated by each RAID extent entry plus one,

ii) selecting a sub-group of storage drives from the group of storage drives, wherein the selected sub-group contains storage drives in the group of storage drives having individual physical capacities that are not less than the physical capacity of any storage drive not contained in the selected sub-group, and wherein a total number of storage drives contained in the selected sub-group is equal to the minimum drive count,

iii) assigning an individual effective capacity to each one of the storage drives contained in the selected sub-group, wherein the individual effective capacity assigned to each one of the storage drives contained in the selected sub-group is equal to an individual physical capacity of a storage drive contained in the selected sub-group that has a smallest individual physical capacity of any storage drive contained in the selected sub-group,

iv) assigning an individual effective capacity to each one of the storage drives in the group of storage drives that is not contained in the selected sub-group, wherein the individual effective capacity assigned to each one of the storage drives in the group of storage drives that is not contained in the selected sub-group is equal to that to the physical capacity of that storage drive,

v) generating a total effective capacity of the group of storage drives that is equal to a sum of the all the individual effective capacities assigned to the storage drives in the group of storage drives, and

vi) setting the effective capacity of the drive extent pool to the total effective capacity of the group of storage drives.