Logical partitioning of a redundant array storage system

• US 6,154,854 A
• Filed: 01/08/1998
• Issued: 11/28/2000
• Est. Priority Date: 11/09/1990
• Status: Expired due to Fees

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Stallmo, David Charles
• Primary Examiner(s): Baker, Stephen M.
• Application Number:
  US09/004,671
• Time in Patent Office: 1,055 Days
• Field of Search: 714/6, 714/7, 711/114
• US Class Current: 714/6.12
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/2087 with a common controller
• CPC Class Codes: G06F 2211/103 Hybrid, i.e. RAID systems with parity comprising a mix of RAID types
• 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 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence

Abstract

A redundant array storage system that can be configured as a RAID 1, 3, 4, or 5 system, or any combination of these configurations. The invention comprises a configuration data structure for addressing a redundant array storage system, and a method for configuring a redundant array storage system during an initialization process. The redundant array storage system comprises a set of physical storage units which are accessible in terms of block numbers. The physical storage units are each configured as one or more logical storage units. Each logical storage unit is addressed in terms of a channel number, storage unit number, starting block number, offset number, and number of blocks to be transferred. Once logical storage units are defined, logical volumes are defined as one or more logical storage units, each logical volume having a depth characteristic. After the logical volumes are defined, redundancy groups are defined as one or more logical volumes. A redundancy level is specified for each redundancy group. The redundancy level may be none, one, or two. Logical volumes are addressed by a host CPU by volume number, initial block number, and number of blocks to be transferred. The host CPU also specifies a READ or WRITE operation. The specified volume number, initial block number, and number of blocks to be transferred are then translated into a corresponding channel number, storage unit number, starting block number, offset number, and number of blocks to be transferred. With the present invention, it is possible for a logical volume to span across physical storage units ("vertical partitioning"), comprise only a portion of each such physical storage unit ("horizontal partitioning"), and have definable depth and redundancy characteristics.

Claims

1. A storage subsystem for use in conjunction with a system central processing unit that issues data requests to said storage subsystem, said data requests being mapped by said system central processing unit to respective addresses that appear to said system central processing unit to be addressed within said storage subsystem, comprising:

a plurality of physical data storage units that are accessible in terms of block numbers and configured as one or more logical storage units, wherein the logical storage units are dynamically configurable into two or more logical volumes, wherein each of said logical volumes comprises a subset of said plurality of physical data storage units, and wherein each of said two or more logical volumes may be configured as separate redundancy groups; and

a storage controller for remapping a specified logical volume, an initial block volume, and a number of blocks mapped by said system central processing unit to actual addresses within said storage subsystem for accessing data structures of the logical volumes transparent to the system central processing unit.

2. The storage subsystem of claim 1 wherein said separate redundancy groups comprise at least two redundancy groups having substantially equivalent RAID levels.

3. The storage subsystem of claim 1 wherein said separate redundancy groups comprise at least two redundancy groups having differing RAID levels.

4. The storage subsystem of claim 1 wherein said two or more logical volumes are configurable at initialization of said storage subsystem.

5. The storage subsystem of claim 1 wherein said two or more logical volumes are configurable at a time when normal access operations are not in progress.

6. The storage subsystem of claim 1 wherein said two or more logical volumes are configurable without halting normal access operations.

7. A method for dynamically configuring a storage subsystem comprising a storage controller coupling a plurality of physical data storage units to a host central processing unit, said method comprising the steps of:

configuring each of the physical data storage units as one or more logical storage units;

partitioning at least some of said logical storage units into two or more logical volumes;

configuring each of said two or more logical volumes as separate redundancy groups;

receiving from said host central processing unit a specified logical volume, an initial block volume, and a number of blocks which has been mapped by said host central processing unit into a host address directed to said storage subsystem;

remapping said host address to an address within said logical volumes; and

using said remapped address, accessing data structures of the logical volumes transparently to said host central processing unit.

8. The method of claim 7 wherein said step of partitioning is carried out by the step of:

logically segregating said plurality of physical data storage units into a number of subsets thereof, each of said subsets corresponding to one of said two or more logical volumes.

9. The method of claim 7 wherein said step of configuring is carried out by the step of:

defining at least two of said logical volumes as redundancy groups having substantially equivalent RAID levels.

10. The method of claim 7 wherein said step of configuring is carried out by the step of:

defining at least two of said logical volumes as redundancy groups having differing RAID levels.

11. The method of claim 7 wherein said step of configuring is carried out at initialization of said storage subsystem.

12. The method of claim 7 wherein said step of configuring is carried out when normal access operations are not in progress.

13. The method of claim 7 wherein said step of configuring is carried out without halting normal access operations.