Multiple user multimedia data server with switch to load time interval interleaved data to plurality of time interval assigned buffers

• US 5,594,924 A
• Filed: 05/18/1995
• Issued: 01/14/1997
• Est. Priority Date: 01/21/1994
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Van Leeuwen, George W., Ottesen, Hal H., Smith, Gordon J.
• Primary Examiner(s): Kim, Ken S.
• Application Number:
  US08/443,838
• Time in Patent Office: 607 Days
• Field of Search: 395/250, 395/550, 395/728, 395/851, 348/7, 370/54, 370/58.2, 370/58.3
• US Class Current: 710/31
• CPC Class Codes: G11B 19/20 Driving; Starting; Stopping; Control thereof
• CPC Class Codes: G11B 19/2009 Turntables, hubs and motors for disk drives; Mounting of motors in the drive means for clamping of disk to turntable G11B17/022 and subgroups
• CPC Class Codes: G11B 19/247 using electrical means
• CPC Class Codes: G11B 20/12 Formatting, e.g. arrangement of data block or words on the record carriers within interface between computers and data recorders G06F3/06
• CPC Class Codes: G11B 20/1258 where blocks are arranged within multiple radial zones, e.g. Zone Bit Recording or Constant Density Recording discs, MCAV discs, MCLV discs
• CPC Class Codes: G11B 2020/10916 Seeking data on the record carrier for preparing an access to a specific address
• CPC Class Codes: G11B 21/00 Head arrangements not specific to the method of recording or reproducing
• CPC Class Codes: G11B 21/02 Driving or moving of heads
• CPC Class Codes: G11B 21/04 Automatic feed mechanism producing a progressive transducing traverse of the head in a direction which cuts across the direction of travel of the recording medium, e.g. helical scan , e.g. by lead-screw G11B19/20, G11B21/08 and G11B21/10 take precedence
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 2220/41 Flat as opposed to hierarchical combination, e.g. library of tapes or discs, CD changer, or groups of record carriers that together store one title
• CPC Class Codes: G11B 2220/415 Redundant array of inexpensive disks [RAID] systems
• CPC Class Codes: G11B 27/002 Programmed access in sequence to a plurality of record carriers or indexed parts, e.g. tracks, thereof, e.g. for editing; transfer of record carriers from magazine G11B15/68, G11B17/10; G11B17/22
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/5521 across disk tracks spiral track following G11B5/596
• CPC Class Codes: G11B 5/5526 Control therefor; circuits, track configurations or relative disposition of servo-information transducers and servo-information tracks for control thereof G11B5/556 takes precedence
• CPC Class Codes: G11B 5/5965 Embedded servo format G11B5/59655 takes precedence
• CPC Class Codes: G11B 7/0037 with discs
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

A disk drive stores multimedia data in long spiral data tracks. The tracks on opposite surfaces of the disk spiral in opposite directions, so that a track on one surface can be read as the actuator sweeps in, and a track on the opposite surface can be read as the actuator sweeps out. Because the actuator only follows spiral tracks without performing long seek operations, the actuator motor can be reduced in size and stresses on actuator bearings and other parts are reduced. Additionally, due to reduced disturbances associated with seeks, it is possible to follow tracks more closely and therefore reduce the width of individual tracks. Further cost reductions are accomplished by spinning the disks at a slower speed and reducing the size of the spin motor accordingly. Finally, data density can be increased simply because multimedia data does not require the same low error rate as conventional data. Preferably, a group of disk drives optimized for multimedia data is used to form a video-on-demand system. Compressed, interleaved portions of a video presentation, such as a motion picture, are stored in blocks on the spiral tracks. The drives read the blocks on one spiral track at a time from beginning to end, placing the data from these blocks in a set of buffers corresponding to different short time intervals. Video signals are output from the buffers. Any short time interval of the presentation can be accessed on demand by switching to the appropriate buffer.

Claims

1. A multimedia data server, comprising:

a plurality of data buffers, each of said buffers corresponding to a respective time interval associated with a multimedia presentation, each buffer having a respective output port for outputting multimedia data stored in said buffer;

at least one mass storage device for storing a multimedia data presentation, wherein multimedia data stored on said mass storage device comprises a plurality of sequentially stored data segments, each data segment being associated with one of said time intervals,

wherein a plurality of data segments is associated with each said time interval, and wherein successive sequentially stored-data segments on said at least one mass storage device are associated with different ones of said time intervals, the data segments associated with a particular one of said plurality of time intervals being interleaved among data segments associated with other time intervals;

at least one data bus connected to said at least one mass storage device for communicating multimedia data from said at least one mass storage device to said buffers;

a plurality of switches connecting said data bus with said plurality of data buffers, each switch being associated with a respective one of said data buffers; and

a controller for operating said plurality of switches, said controller causing a switch associated with a selected data buffer to close when said at least one mass storage device outputs a data segment on said data bus associated with said a time interval corresponding to the selected data buffer.

2. The multimedia data server of claim 1, wherein said at least one data storage device comprises a rotating disk drive storage device in which data is stored on at least one spiral data track.

3. The multimedia data server of claim 2, wherein said spiral data track of said rotating disk drive storage device contains a plurality of data segments associated with a repetitive sequence of at least some of said plurality of time intervals.

4. The multimedia data server of claim 1, wherein said server comprises at least two mass storage devices.

5. The multimedia data server of claim 4, wherein:

data is stored redundantly on said mass storage devices, and said controller detects a failure of one of said mass storage devices, and in response to said failure causes redundant data stored on mass storage devices other than the failing mass storage device to be provided to said buffers in lieu of data stored on said failing mass storage device.

6. The multimedia data server of claim 5, further comprising at least one back-up switch operable by said controller, each switch associated with a respective one of said at least one data bus, each switch selectively coupling one of a plurality of said mass storage devices to the data bus with which said switch is associated.