US 2003/0170012 A1 · Method and system for reliable remote-mirror resynchronization in disk arrays and other mass storage devices

Abstract

On a dominant logical unit provided by a mass-storage device, hot spare disks are employed to create a much larger, disk-based time-ordered WRITE-request buffer that spans, in one embodiment, both electronic memory and hot spare disks. The much larger time-ordered WRITE-request buffer in the modified dominant logical unit allows for storing WRITE requests in time order for a much longer period of time during communications failure between the dominant logical unit and remote-mirror logical unit than in the current techniques that employ only an electronic-memory-based time-ordered WRITE-request buffer. On the remote-mirror logical unit, mass-storage space is provided for an alternate logical unit that can be resynchronized with the dominant logical unit following restoration of communications between the dominant logical unit and remote-mirror logical unit. When resynchronization is complete, a simple logical-unit-pointer switch operation can be employed to designate the alternate logical unit as the new remote-mirror logical unit, and the previous remote-mirror logical unit as the alternate logical unit.

Claims21

Dependent claims

A method for storing WRITE requests in a dominant mass-storage device for later forwarding to a remote mass-storage device that provides mirroring of data stored in the dominant mass-storage device, the method comprising:

providing a time-ordered WRITE request buffer stored in spare mass-data-storage components within the dominant mass-storage device;
buffering WRITE requests within the time-ordered WRITE request buffer until the time-ordered WRITE request buffer is filled;
and
when the time-ordered WRITE request buffer is filled, converting the time-ordered WRITE request buffer to a bit-map WRITE request buffer and setting a bit in the bit-map WRITE request buffer for each additional unit of data storage modified by received WRITE requests.

1 more element

Dependencies are inferred from the claim text.

Method and system for reliable remote-mirror resynchronization in disk arrays and other mass storage devices

Life of this patent

Method and system for reliable remote-mirror resynchronization in disk arrays and other mass storage devices

Life of this patent

Abstract

Claims21