Methods and structure for RAID level migration within a logical unit

• US 6,275,898 B1
• Filed: 05/13/1999
• Issued: 08/14/2001
• Est. Priority Date: 05/13/1999
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: DeKoning, Rodney A.
• Primary Examiner(s): Kim, Matthew
• Assistant Examiner(s): CHACE, CHRISTIAN
• Application Number:
  US09/311,316
• Time in Patent Office: 824 Days
• Field of Search: 711/114, 714/6, 714/7
• US Class Current: 711/114
• CPC Class Codes: G06F 2211/1004 Adaptive RAID, i.e. RAID system adapts to changing circumstances, e.g. RAID1 becomes RAID5 as disks fill up
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0629 Configuration or reconfiguration of storage systems
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

Methods and structures for defining partitions within a RAID storage system LUN such that each partition is managed in accordance with RAID management techniques independent of the other partitions. The total data storage of the LUN is subdivided and mapped into a plurality of partitions also referred to as partitions. Initially, each partition is configured and mapped to run as a RAID level 1 mirrored storage area. As performance and storage capacity needs as measured for each partition dictate, a partition of a LUN may be reconfigured to use a different RAID level (i.e., level 3 or 5) to reduce overhead storage needs at the cost of decreased write performance. A partition may later be returned to RAID level 1 as performance needs so indicate. Each partition is therefore managed in accordance with its own RAID level of management. The partitions of a LUN may expand to incorporate unused space in an adjacent partition or unused space in the LUN may be compacted and consolidated in one area of the LUN such that the partitions are moved to fill holes in the LUN storage capacity.

Claims

1. A method for enabling automatic reconfiguration of storage space in a storage system having a plurality of disk drives comprising the steps of:

defining a logical unit in said storage system as a subset of the storage space of said storage system;

configuring a plurality of partitions within said logical unit; and

reconfiguring at least one partition of said plurality of partitions in response to measured parameters of operation of said storage system,

wherein the step of reconfiguring is automatically operable within the storage system independent of any external operator.

2. The method of claim 1

wherein the step of configuring includes the step of assigning an initial storage management technique to each partition of said plurality of partitions, and

wherein the step of reconfiguring includes the step of changing said storage management technique assigned to at least one partition of said plurality of partitions.

3. The method of claim 2

wherein the step of assigning comprises the step of initializing said each partition for RAID level 1 mirrored operation, and

wherein the step of changing comprises the step of compacting data in said at least one partition to reconfigure said at least one partition for a RAID level of operation higher than RAID level 1.

4. The method of claim 3 wherein the step of reconfiguring further includes the step of restoring RAID level 1 mirrored operation to said at least one partitions.

5. The method of claim 1

wherein the step of configuring includes the step of allocating an initial storage space for each partition of said plurality of partitions, and

wherein the step of reconfiguring includes the step of changing the allocated storage space of at least one partition of said plurality of partitions.

6. The method of claim 5 wherein the step of reconfiguring further includes restoring the allocated storage space of said at least one partition to said initial storage space.

7. A system comprising:

a plurality of disk drives; and

a storage controller coupled to said plurality of disk drives and coupled to a host system to process I/O requests received from said host system wherein said storage controller includes;

a logical unit configuration manager operable to define a logical unit within said plurality of disk drives;

a partition configuration manager associated with said logical unit configuration manager and operable to define a plurality of partitions within said logical unit; and

a performance monitor coupled to said partition configuration manager to measure parameters associated with operation of said storage system wherein said partition configuration manager is responsive to said performance monitor to modify configuration parameters of at least one partition of said plurality of partitions in response to measurements of said performance monitor,

wherein said performance monitor and said partition configuration manager are automatically operable independent of any external operator.

8. The system of claim 7 wherein said performance monitor includes:

access time monitor for detecting a need for improved access time for data in any partition of said plurality of partitions; and

storage utilization monitor for detecting a need for reduction in storage overhead utilization in any partition of said plurality of partitions.

9. The system of claim 8 wherein said partition configuration manager includes:

a partition type manager to modify a storage management technique associated with a partition in response to said performance monitor.

10. The system of claim 9 wherein each partition of said plurality of partitions is managed in accordance with a RAID storage management level and wherein said partition type manager includes:

a partition promoter to promote a partition to RAID level 1 management in response to detection of a need for improved access time.

11. The system of claim 9 wherein each partition of said plurality of partitions is managed in accordance with a RAID storage management level and wherein said partition type manager includes:

a partition demoter to demote a partition from RAID level 1 to another RAID level of management using less storage overhead in response to detection of a need to reduce storage overhead utilization.

12. The system of claim 9 wherein each partition of said plurality of partitions is managed in accordance with a RAID storage management level and wherein said partition type manager includes:

a partition demoter to demote a partition from RAID level 1 to another RAID level of management in response to detection of a need for increased bandwidth for access to said partition.

13. A storage controller for managing data storage on a plurality of disk drives in a storage system, said controller comprising:

means for defining a RAID logical unit comprising a subset of said plurality of disk drives;

means for defining a plurality of partitions within said logical unit;

means for monitoring performance of access to said RAID logical unit; and

means, coupled with said means for monitoring performance, for reconfiguring said plurality of partitions in response to performance measurements of said means for monitoring performance,

wherein said means for monitoring and said means for reconfiguring are automatically operable independent of any external operator.

14. The controller of claim 13 wherein said means for monitoring performance includes:

access time monitor means for detecting a need for improved access time for data in any partition of said plurality of partitions; and

storage utilization monitor means for detecting a need for reduction in storage overhead utilization in any partition of said plurality of partitions.

15. The system of claim 14 wherein each partition of said plurality of partitions is managed in accordance with a RAID storage management level and wherein said means for reconfiguring includes:

partition promotion means for promoting a partition to RAID level 1 management in response to detection of a need for improved access time by said access time monitor means; and

partition demotion means for demoting a partition from RAID level 1 to another RAID level of management using less storage overhead in response to detection of a need to reduce storage overhead utilization by said storage utilization monitor means.