US 6,502,205 B1 · Asynchronous remote data mirroring system

Abstract

Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary volume, and data written to a primary volume is automatically sent over the link to a corresponding secondary volume. Each remotely mirrored volume pair can operate in a selected synchronization mode including synchronous, semi-synchronous, adaptive copy-remote write pending, and adaptive copy-disk. Direct write access to a secondary volume is denied if a “sync required” attribute is set for the volume and the volume is not synchronized. If a “volume domino” mode is enabled for a remotely mirrored volume pair, access to a volume of the pair is denied when the other volume is inaccessible. In a “links domino” mode, access to all remotely mirrored volumes is denied when remote mirroring-is disrupted by an all-links failure. The domino modes can be used to initiate application-based recovery, for example, recovering a secondary data file using a secondary log file. In an active migration mode, host processing of a primary volume is concurrent with migration to a secondary volume. In an overwrite cache mode, remote write-pending data in cache can be overwritten. Write data for an entire host channel command word chain is bundled in one link transmission.

Claims8

Dependent claims

A system for automatically providing remote copy storage of data from a host computer, said system comprising:

a first data storage system for coupling to the host computer for storing data from the host computer;
and
a second data storage system remotely coupled to the first data storage system for receiving a copy of the data from the first data storage system;
wherein the first data storage system is programmed to transmit the data from the host computer to secondary storage in the second data storage system together with an indication that a primary storage device in the first data storage system is not available when the primary storage device in the fist data storage system is not available for storing the data from the host computer, and when the primary storage device in the first data storage system becomes available, the first data storage system automatically resynchronizes the primary storage device with the secondary storage in the second data storage system.

1 more element

A system for maintaining substantially mirrored copies of data at geographically removed locations for recovery from a disaster, said system comprising:

a first data storage system for coupling to a host computer for storing data from the host computer;
the first data storage system being located at a first geographical location;
and
a second data storage system coupled to the first data storage system for receiving a copy of the data from the first data storage system, the second data storage system being located at a second geographical location, the second geographical location being geographically removed from the first geographic location;
wherein the first data storage system is programmed to:
(a) store the data from the host computer to primary storage in the first data storage system to create a primary copy of the data in the first data storage system;
(b) maintain a list of the data to be transmitted from the first data storage system to the second data storage system for storage of the data to secondary storage in the second data storage system to create a secondary copy of the data in the second data storage system;
(c) coordinate and control, without intervention from the host computer, transmission of the data from the first data storage system to the second data storage system;
(d) update said list in response to acknowledgements from the secondary data storage system of receipt of the data transmitted from the first data storage system to the second data storage system;
and
(e) acknowledge to the host computer that the data from the host computer has been stored before the first data storage system has received a corresponding acknowledgement from the secondary data storage system of receipt of the data transmitted from the first data storage system.

8 more elements

Dependencies are inferred from the claim text.

Asynchronous remote data mirroring system

Life of this patent

Asynchronous remote data mirroring system

Life of this patent

Abstract

Claims8