Disk-based digital video recorder

• US 5,574,662 A
• Filed: 06/01/1995
• Issued: 11/12/1996
• Est. Priority Date: 09/21/1992
• Status: Expired due to Term

• Current Assignee: Grass Valley USA LLC (Vislink Technologies, Inc.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: O'Connor, Paul, Casper, David, Murray, Scott, Greco, Anna, Windrem, Kevin D., Zamani, Elaine B.
• Primary Examiner(s): Ramirez, Ellis B.
• Application Number:
  US08/457,895
• Time in Patent Office: 530 Days
• Field of Search: 364/514 R, 364/514 A, 348/7, 348/13, 338/342, 395/438, 395/441, 395/404, 395/411
• US Class Current: 709/219
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 12/0862 with prefetch
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• CPC Class Codes: G11B 20/1833 by adding special lists or symbols to the coded information G11B20/1806, G11B20/1866 take precedence
• CPC Class Codes: H04N 5/781 on disks or drums
• CPC Class Codes: H04N 5/9261 involving data reduction

Abstract

A digital video recorder employing standard hard disk arrays employs a caching system to enable continuous video data to be supplied to and provided from the standard disk drives which may not be adapted for continuous data stream operation. The system is implemented as an array of disk drives and includes cache management functions for governing disk read and write operations. A predictor enables the cache to predict disk reads and disk writes and to maintain the cache based on the predictions. Redundancy enables playback in the event of failure of a drive in the array and also provides improved playback data retrieval time.

Claims

1. A method for retrieving information from an array of n data storage devices, said array including one redundant storage device, comprising the steps of:

requesting information from the array of data storage devices;

retrieving data from the first n-1 data storage devices to respond to the request for information; and

deriving the information based on the retrieved data, thereby enabling information retrieval without waiting for the response of the last data storage device.

2. The method according to claim 1, wherein the information is stored on the array of storage devices by a storage method comprising the steps of:

storing information on n-1 storage devices;

determining redundancy data from the information; and

storing the determined redundancy data on the nth data storage device;

3. The method according to claim 2, wherein said step of determining redundancy data comprises exclusive ORing portions of information stored on each of the n-1 storage devices.