Method for transaction command ordering in a remote data replication system

• US 6,658,540 B1
• Filed: 03/31/2000
• Issued: 12/02/2003
• Est. Priority Date: 03/31/2000
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Walker, Michael D., Sicola, Stephen J., Lary, Richard F., Elkington, Susan G.
• Primary Examiner(s): Bragdon, Reginald G.
• Assistant Examiner(s): Inoa, Midys
• Application Number:
  US09/540,309
• Time in Patent Office: 1,341 Days
• Field of Search: 711/161, 711/162, 707/204
• US Class Current: 711/162
• CPC Class Codes: G06F 11/2007 using redundant communication media
• CPC Class Codes: G06F 11/201 between storage system components
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

A disaster-tolerant data backup and remote copy system which is implemented as a controller-based replication of one or more LUNs (logical units) between two remotely separated pairs of array controllers connected by redundant links. The system provides a method for allowing a large number of commands to be ‘outstanding’ in transit between local and remote sites while ensuring the proper ordering of commands on remote media during asynchronous or synchronous data replication. In addition, the system provides a mechanism for automatic ‘tuning’ of links based on the distance between the array controllers.

Claims

1. A method for copying data, written by a host computer to a local data storage array, to backup a copy of the data on a remote storage system, wherein a local array controller, connected to the local data storage array, is coupled to a remote array controller connected to the remote storage system, the method comprising the steps of:

sending a plurality of write commands, associated with the data, from the local array controller to the remote array controller;

in the situation wherein a first one of the write commands completes before a second one of the write commands starts at the local site, then inhibiting said data associated with the second one of the write commands from being recorded to media on the remote storage system before said data associated with the first one of the write commands is recorded to media on the remote storage system; and

using a sliding window protocol in said sending step to protect against out-of-order receptions at the remote site.

2. A method for copying data, written by a host computer to a local data storage array, to backup a copy of the data on a remote storage system, wherein a local array controller, connected to the local data storage array, is coupled to a remote array controller connected to the remote storage system, the method comprising the steps of:

sending a plurality of write commands, associated with the data, from the local array controller to the remote array controller; and

in the situation wherein a first one of the write commands completes before a second one of the write commands starts at the local site, then inhibiting said data associated with the second one of the write commands from being recorded to media on the remote storage system before said data associated with the first one of the write commands is recorded to media on the remote storage system.

3. The method of claim 2, wherein a sliding window protocol is used in said sending step to protect against out-of-order receptions at the remote site.

4. A method for copying data, written by a host computer to a local data storage array, to backup a copy of the data on a remote storage system, wherein a local array controller, connected to the local data storage array, is coupled to a remote array controller connected to the remote storage system, wherein a plurality of write commands, associated with the data, are sent from the local array controller to the remote array controller, the method comprising the step of:

in the situation wherein a first write command completes before a second write command starts at the local site, then inhibiting said data associated with the second write command from being recorded to media on the remote storage system before the first write command is recorded to media at the remote site.

5. The method of claim 4, wherein a sliding window protocol is used to protect against out-of-order receptions at the remote site.