Method and system for minimizing client perceived latency through effective use of memory in video-on-demand clusters

• US 20070239882A1
• Filed: 04/10/2006
• Published: 10/11/2007
• Est. Priority Date: 04/10/2006
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ratakonda, Krishna, Lai, Junwen, Turaga, Deepak, Lee, Nathan
• Application Number:
  US11/400,363
• Publication Number:
  US 20070239882A1
• Time in Patent Office: Days
• US Class Current: 709/231
• CPC Class Codes: H04L 65/103 in the network
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 65/765 intermediate
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching

Abstract

A method (and system) of transferring data of multimedia objects from servers to clients using memory in video-on-demand clusters, includes dividing multimedia objects into segments and independently serving and caching the segments on a plurality of servers, retrieving the segments from the servers, directing the client to the server that is responsible for serving the at least one of the segments using a redirection algorithm, and predicting a likely sequence of segments that will be requested by the client and prefetching data from a next segment in the likely sequence of segments and loading the next segment into memory within one of the plurality of servers.

Claims

1. A method of transferring data of multimedia objects from servers to clients using memory in video-on-demand clusters, comprising:

dividing multimedia objects into segments and independently serving and caching said fixed-size segments on a plurality of servers;

retrieving said segments from said servers, said retrieving comprising;

requesting at least one of said segments from a centralized director;

returning an address of a server that is responsible for serving said at least one of said segments to a client;

requesting said at least one of said segments from said server that is responsible for serving said at least one of said segments; and

streaming data from said server that is responsible for serving said at least one of said segments to the client; and

directing the client to said server that is responsible for serving said at least one of said segments using a redirection algorithm.

2. The method of transferring data according to claim 1, wherein a server for storing fetched data is selected from said plurality of servers based on a load of said plurality of servers.

3. The method of transferring data according to claim 1, wherein said dividing multimedia objects into segments is performed based on a request popularity of said multimedia objects.

4. The method of transferring data according to claim 1, wherein each time a client request is received for a new segment, said redirection algorithm is run to decide which server of said plurality of servers should receive the client request.

5. The method of transferring data according to claim 4, wherein said redirection algorithm decides which server of said plurality of servers should receive the client request by calculating an amount of memory available on a server,

wherein R_i=M_i−

C_i is the memory still available on a server i, and

wherein said redirection algorithm calculates the load L_i on each server i, each server having M_i units of main memory, of N number of servers, where L_i is defined as a total network bandwidth requirement of all the clients the server is serving, a number of clients accessing segment k on server i is n_ik, an amount of memory that segment k consumes on server i is (1−

e<sup>−

nik</sup>)B_k, where B_k is the size of the segment, and a total memory consumption C_i of server i is

$C_i=\underset{k}{\sum <br><br>}<br><br>\left(1-{\mathrm{e<br><br>}}^{-n_{\mathrm{ik}}}\right)<br><br>B_k.$

6. The method of transferring data according to claim 5, wherein the redirection algorithm maintains a home server for each segment, which corresponds to a server in which the segment is loaded into memory,

wherein the redirection algorithm selects a server to act as the home server by selecting a server having a maximal R_i/L_i ratio, and

wherein subsequent requests for the segment are redirected to the home server until a load on the home server increases to at least twice as much as an average server load, and then a new home server for the segment is selected.

7. The method of transferring data according to claim 1, wherein said segments comprise fixed-size segments.

8. The method of transferring data according to claim 1, wherein said segments comprise variable-size segments.

9. The method of transferring data according to claim 8, wherein a length of said variable-size segments is determined by a popularity of the segments.

10. The method of transferring data according to claim 8, wherein a length of said variable-size segments is determined by a load of the server.

11. The method of transferring data according to claim 8, wherein a length of said variable-size segments is determined by a popularity of the segments and a load of the server.

12. The method of transferring data according to claim 1, further comprising:

predicting a likely sequence of segments that will be requested by the client and pre-fetching data from a next segment in said likely sequence of segments and loading said next segment into memory within one of said plurality of servers.