# US 2014/0195732 A1 · METHOD AND SYSTEM TO MAINTAIN MAXIMUM PERFORMANCE LEVELS IN ALL DISK GROUPS BY USING CONTROLLER VDs FOR BACKGROUND TASKS

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- Number: US 2014/0195732 A1
- Document ID: US20140195732A1
- Status: Published application
- Kind: A1
- Application number: 13/736,149
- Filed: 2013-01-08
- Published: 2014-07-10
- Earliest claimed: 2013-01-08
- Assignees: LSI Corporation
- Applicants: Lsi Corporation
- Inventors: Hariharan T.; Madan Mohan Munireddy
- Web page: https://patentgrep.com/patent/US20140195732A1

## CPC

- G06F 12/0871: Allocation or management of cache space
- G06F 12/0831: using a bus scheme, e.g. with bus monitoring or watching means
- G06F 12/0866: for peripheral storage systems, e.g. disk cache
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

Disclosed is a system and method for performing reconstruction or on-line capacity expansion, background tasks, on a disk group configured on a controller with minimal impact on the other disk groups configured on the same controller. A user is enabled to continuously experience increased performance on all source virtual disks configured on the controller since the DRAM is always dedicated for I/O performance.

## Claims

### Claim 1

A method of performing a background operation on a first disk group while at least one other disk group performs normal caching, wherein each of said first and other disk groups comprises cache contents, said method comprising:
determining if there are any write-through Secondary Cache disks configured;
if a write-through disk is configured;
invalidating the cache contents of the write-through Secondary Cache disk;
dissociating the Secondary Cache write-through disk from a source disk; and
using the write-through Secondary Cache disk for the background function;
if a write-through Secondary Cache disk is not configured;
identifying a suitable write-back Secondary Cache disk;
flushing the cached contents of the suitable write-back Secondary Cache disk to a respective source disk;
dissociating the write-back Secondary Cache disk from the source disk; and
using the write-back Secondary Cache disk for the background operation; and
upon completing of the background operation;
restoring Secondary Cache disk cache policies; and
reverting any dissociated disks back to being associated with a source disk as originally associated.

### Claim 2 (depends on 1)

The method of claim 1, wherein said background function comprises a reconstruction or an on-line capacity expansion.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
the steps associated with if a write-through disk is configured are performed by firmware; and
the steps associated with if a write-through disk is not configured are performed by firmware.

### Claim 4 (depends on 1)

The method of claim 1, said method further comprising enabling the background function.

### Claim 5 (depends on 4)

The method of claim 4, said method further comprising continuing normal data caching operations.

### Claim 6 (depends on 4)

The method of claim 4, wherein:
the steps associated with if a write-through disk is configured are performed by firmware; and
the steps associated with if a write-through disk is not configured are performed by firmware.

### Claim 7 (depends on 6)

The method of claim 6, wherein said background function comprises a reconstruction or an on-line capacity expansion.

### Claim 8

A system for performing background tasks on a plurality of disk groups, said system comprising:
a controller enabled to perform the background tasks on said plurality of disks, wherein:
the controller determines if a write-through virtual disk is configured;
if a write-through virtual disk is configured, the controller invalidates any contents of the write-through disk cache;
if a write-through virtual disk is not configured, the controller identifies a suitable write-back virtual disk and flushes data from the write-back virtual disk;
the controller uses the virtual disk for the background task; and
when the background task is complete, the controller reverts the virtual disk associations and cache policies back.

### Claim 9 (depends on 8)

The method of claim 8, wherein said background tasks comprise reconstruction and on-line capacity expansion.

### Claim 10 (depends on 8)

The method of claim 8, further wherein the controller continues normal data caching operations.

### Claim 11 (depends on 10)

The method of claim 10, wherein said background tasks comprise reconstruction and on-line capacity expansion.