Video file server using an integrated cached disk array and stream server computers

• US 6,061,504 A
• Filed: 06/10/1996
• Issued: 05/09/2000
• Est. Priority Date: 10/27/1995
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Duso, Wayne W, Alagappan, Kannan M, Tzelnic, Percy, Ting, Dennis P. J., Vaitzblit, Lev, Forecast, John, Vahalia, Uresh K
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): LE, UYEN T
• Application Number:
  US08/661,152
• Time in Patent Office: 1,429 Days
• Field of Search: 395/200.49, 395/200.48, 395/200.47, 395/200.31, 395/200.32, 395/200.33, 395/182.04, 395/600, 395/200.64, 395/872-877, 395/894, 364/514 A, 711/113
• US Class Current: 709/219
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 11/1461 Backup scheduling policy
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: H04L 65/1063 Application servers providing network services systems providing special services to telephonic subscribers H04M3/42
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/611 for multicast or broadcast systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 65/762 at the source reformatting of additional data in video distribution servers H04N21/2355
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04N 21/2182 involving memory arrays, e.g. RAID disk arrays RAID arrays per se G06F3/0689; use of parity to protect data in RAID systems G06F11/1008
• CPC Class Codes: H04N 21/23106 involving caching operations prefetching while addressing of a memory level in which the access to the desired data or data block requires associative addressing means within memory systems or architectures G06F12/0862; caching at an intermediate stage in a data network H04L67/568
• CPC Class Codes: H04N 21/2396 characterized by admission policies admission control, resource allocation in open networks H04L12/5692; arrangements for network security using user profiles for access control H04L63/102; access security in wireless networks H04W12/08
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

A video file server includes an integrated cached disk array storage subsystem and a plurality of stream server computers linking the cached disk storage system to the data network for the transfer of video data streams. The video file server further includes a controller server for applying an admission control policy to client requests and assigning stream servers to service the client requests. The stream servers include a real-time scheduler for scheduling isochronous tasks, and supports at least one industry standard network file access protocol and one file access protocol for continuous media file access. The cached disk storage subsystem is responsive to video prefetch commands, and the data specified for a prefetch command for a process are retained in an allocated portion of the cache memory from the time that the cached disk storage subsystem has responded to the prefetch command to the time that the cached disk storage subsystem responds to a fetch command specifying the data for the process. The time between prefetching and fetching is selected based on available disk and cache resources. The video file server provides video-on-demand service by maintaining and dynamically allocating sliding windows of video data in the random access memories of the stream server computers.

Claims

1. A file server for serving clients in a data network, said file server comprising:

a cached disk array storage subsystem; and

a plurality of server computers linking the cached disk array storage subsystem to said data network for-responding to a request for file access from a client in the data network by transferring data between said cached disk array storage subsystem and said data network;

wherein the cached disk array storage subsystem includes a semiconductor cache memory, an array of disk drives, a plurality of channel directors for interfacing said semiconductor cache memory to said server computers, and a plurality of disk directors and disk adapters for interfacing said semiconductor cache memory to said array of disk drives; and

wherein the file server further includes a controller linked to said network and said server computers for responding to a request for file access from a client by selecting one of the server computers to satisfy the request.

2. The file server as claimed in claim 1, wherein each of said server computers has a scheduler program for scheduling isochronous tasks, real-time tasks, and general purpose tasks.

3. A file server for serving clients in a data network, said file server comprising, in combination:

a cached disk array storage subsystem;

a plurality of stream server computers linking the cached disk array storage subsystem to said data network for transfer of data streams between said cached disk array storage subsystem and said data network; and

a controller server connected to said stream server computers for receiving a request for file access from a client in the data network, and for selecting one of the stream server computers to satisfy the request by streaming data between the cached disk array storage subsystem and the data network;

wherein said stream server computers are commodity personal computers, and said controller server is also a commodity personal computer, and said file server includes a spare controller server that is also a commodity personal computer.

4. The file server as claimed in claim 3, wherein said commodity personal computers share a data link internal to said file server and separate from said data network.

5. The file server as claimed in claim 4, further including data terminal linked to said controller server for permitting an operator at said data terminal to communicate with said commodity personal computers.

6. The file server as claimed in claim 3, wherein each of said commodity personal computers is linked to the cached disk array by at least one respective fast, wide differential (FWD) SCSI connection.

7. The file server as claimed in claim 6, further including a data terminal linked to said controller server to permit an operator at said data terminal to manage and control file server resources.

8. The file server as claimed in claim 7, wherein said file server supports a Simple Network Management Protocol (SNMP) for said operator to manage and control said file server resources from the data terminal.

9. A file server for serving clients in a data network, said file server comprising, in combination:

a cached disk array storage subsystem;

a plurality of stream server computers linking the cached disk array storage subsystem to said data network for transfer of data streams between said cached disk array storage subsystem and said data network; and

a controller server connected to said stream server computers for receiving a request for file access from a client in the data network, and for selecting one of the stream server computers to satisfy the request by streaming data between the cached disk array storage subsystem and the data network;

wherein said file server has multiple file systems existing concurrently over multiple communication stacks, with shared data access.

10. A file server for serving clients in a data network, said file server comprising, in combination:

a cached disk array storage subsystem;

a plurality of stream server computers linking the cached disk array storage subsystem to said data network for transfer of data streams between said cached disk array storage subsystem and said data network; and

a controller server connected to said stream server computers for receiving a request for file access from a client in the data network, and for selecting one of the stream server computers to satisfy the request by streaming data between the cached disk array storage subsystem and the data network;

wherein said cached disk array storage subsystem includes a semiconductor cache memory, an array of disk drives, a plurality of channel directors for interfacing said semiconductor cache memory to said stream server computers, and a plurality of disk directors and disk adapters for interfacing said semiconductor cache memory to said array of disk drives.

11. A video file server for serving clients in a data network, said video file server comprising, in combination:

a cached disk array storage subsystem;

a plurality of stream server computers linking the cached disk array storage subsystem to said data network for transfer of video data streams between said cached disk array storage subsystem and said data network; and

a controller server connected to said stream server computers for receiving a request from a client in the data network, for applying an admission control policy to determine whether or not there exist sufficient resources in said cached disk array storage subsystem and said stream server computers to satisfy the request, and for selecting one of the stream server computers to satisfy the request when there exists sufficient resources in said cached disk array storage subsystem and said stream servers to satisfy the request.

12. The video file server as claimed in claim 11, wherein said stream server computers are commodity personal computers, said controller server is a commodity personal computer, and said video file server includes a spare controller server that is also a commodity personal computer.

13. The video file server as claimed in claim 11, wherein at least one of the stream server computers is a spare for use as a replacement for any one of the other stream servers that would experience a failure.

14. The video file server as claimed in claim 12, wherein said commodity personal computers share a data link internal to said video file server and separate from said data network.

15. The video file server as claimed in claim 13, further including a shared data terminal linked to said commodity personal computers in order to permit an operator at said shared data terminal to communicate with said commodity personal computers.

16. The video file server as claimed in claim 12, wherein each of said commodity personal computers is linked to the cached disk array by at least one respective fast, wide differential (FWD) SCSI connection.

17. The video file server as claimed in claim 11, further including a data terminal linked to said controller server to permit an operator at said data terminal to manage and control server resources.

18. The video file server as claimed in claim 17, wherein said controller server supports a Simple Network Management Protocol (SNMP) for said operator to manage and control said server resources from the data terminal.

19. The video file server as claimed in claim 11, wherein said controller server includes an admission control program for determining whether or not there exist sufficient resources in said integrated cached disk array storage subsystem and said stream server computers to satisfy the request, and for selecting one of the stream server computers to satisfy the request when there exists sufficient resources in said integrated cached disk array storage subsystem and said stream servers to satisfy the request.

20. The video file server as claimed in claim 11, wherein each of the stream server computers has a real-time scheduler to schedule local operations required to satisfy operational commands from the controller server.

21. The video file server as claimed in claim 11, wherein said video file server supports at least one industry standard network file access protocol and one file access protocol for continuous media file access.

22. The video file server as claimed in claim 21, wherein said stream servers have multiple file systems existing concurrently over multiple communication stacks, with shared data access.

23. The video file server as claimed in claim 11, wherein said cached disk array storage subsystem includes a semiconductor cache memory, an array of disk drives, a plurality of channel directors for interfacing said semiconductor cache memory to said stream server computers, and a plurality of disk directors and disk adapters for interfacing said semiconductor cache memory to said array of disk drives.

24. A video file server for serving clients in a data network, said video file server comprising, in combination:

a cached disk array storage subsystem;

a plurality of stream server computers linking the cached disk array storage subsystem to said data network for transfer of video data streams between said cached disk array storage subsystem and said data network; and

a pair of redundant controller server computers, said controller server computers being connected to said stream server computers for receiving a request from a client in the data network, for applying an admission control policy to determine whether or not there exist sufficient resources in said cached disk array storage subsystem and said stream server computers to satisfy the request, and for selecting one of the stream server computers to satisfy the request when there exists sufficient resources in said cached disk array storage subsystem and said stream server computers to satisfy the request;

wherein said stream servers computers include a real-time scheduler for scheduling isochronous tasks, real-time tasks, and general purpose tasks; and

wherein said stream server computers support at least one industry standard network file access protocol and one file access protocol for continuous media file access.

25. The video file server as claimed in claim 24, wherein each of said controller server computers and said stream server computers is a commodity personal computer that is linked to the cached disk array by at least one fast, wide differential (FWD) SCSI connection.

26. The video file server as claimed in claim 25, wherein said commodity personal computers share a data link internal to said video file server and separate from said data network.

27. A method of operating a video file server for serving clients in a data network, said video file server including a cached disk array storage subsystem and a plurality of stream server computers linking the cached disk array storage subsystem to said data network for transfer of video data streams between the cached disk array storage subsystem and said data network, said method comprising the steps of:

(a) the video file server receiving a request from a client in the data network; and

then

(b) the video file server applying an admission control policy to determine whether or not there exist sufficient resources in said cached disk array storage subsystem and said stream server computers to satisfy the request;

(c) when said admission control policy determines that there exist sufficient resources in said cached disk array storage subsystem and said stream server computers to satisfy the request, selecting one of the stream server computers to satisfy the request; and

then

(d) using the selected one of the stream server computers to satisfy the request by transferring a video data stream between said cached disk array storage subsystem and said data network.

28. The method as claimed in claim 27, wherein said admission control policy schedules an isochronous task including the transferring of said video stream between said cached disk array storage subsystem and said data network, and said method further includes scheduling real-time and general purpose tasks for said video file server.

29. The method as claimed in claim 27, which includes said video file server providing file access to said network clients by using an industry standard file access protocol, and said video file server providing said video stream to said network by using a file access protocol for continuous media file access.

30. The method as claimed in claim 29, wherein said industry standard file access protocol is NFS.

31. The method as claimed in claim 27, which includes buffering said video stream in a buffer in said selected one of said stream servers.

32. The method as claimed in claim 27, which further includes the video file server controlling a network switching mechanism to establish a data link between said client and said selected one of said stream servers.

33. A method of operating a video file server for serving clients in a data network, said video file server including a cached disk array storage subsystem and a plurality of stream server computers linking the cached disk array storage subsystem to said data network for transfer of video data between said cached disk array storage subsystem and said data network, said method comprising the steps of:

(a) receiving in a controller server a request from a client in the data network, said controller server applying an admission control policy to determine whether or not there exist sufficient resources in said cached disk array storage subsystem and said stream server computers to satisfy the request;

(b) when said admission control policy determines that there exist sufficient resources in said cached disk array storage subsystem and said stream server computers to satisfy the request, said controller server scheduling an isochronous task including the transferring of a video stream between said cached disk array storage subsystem and said data network, and said controller server selecting one of the stream server computers to perform the transferring of said video data stream between said cached disk array storage subsystem and said data network, and said controller server sending an operational command to the selected one of the stream server computers; and

(c) in response to said operational command, the selected one of the stream server computers transferring said video data stream between said cached disk array storage subsystem and said data network.

34. The method as claimed in claim 33, which further includes the selected one of the stream server computers using a real-time scheduler to schedule local operations required to satisfy said operational command from said controller server.

35. The method as claimed in claim 33, wherein only the controller server of the video file server receives network requests from the network clients in order to prevent the video file server from performing conflicting operations in response to concurrent network request from the network clients.

36. The method as claimed in claim 33, which includes said stream server computers scheduling real-time and general purpose tasks for said video file server.

37. The method as claimed in claim 33, which includes said video file server providing file access to said network clients by using an industry standard file access protocol, and said video file server providing said video data stream to said network using a file access protocol for continuous media file access.

38. The method as claimed in claim 37, which includes said video file server concurrently supporting multiple file systems over multiple communication stacks, with shared data access, and exporting to the network clients multiple file systems.

39. The method as claimed in claim 33, which includes said selected one of said stream server computers buffering said video data stream in a buffer in said selected one of said stream server computers.

40. The method as claimed in claim 33, which further includes said controller server communicating with a network switching mechanism to establish a data link between said client and said selected one of said stream server computers.