File system for handling real-time and non-real-time data

• US 6,714,986 B2
• Filed: 11/25/2002
• Issued: 03/30/2004
• Est. Priority Date: 10/26/1995
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Karibe, Tomoyuki, Ito, Yukiko, Tamai, Masaaki, Doi, Shinzo, Tanaka, Tsutomu, Kokado, Takeshi
• Primary Examiner(s): Von Buhr, Maria N.
• Application Number:
  US10/303,014
• Publication Number:
  US 20030074374A1
• Time in Patent Office: 491 Days
• Field of Search: 707/100-102, 707/10, 709/102-104, 709/200-203, 709/227-229, 709/232-235, 709/238-244, 725/86-97, 725/101-103, 710/20, 710/21, 710/29, 710/58-61
• US Class Current: 709/240
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/234381 by altering the temporal resolution, e.g. decreasing the frame rate by frame skipping
• CPC Class Codes: H04N 21/23805 Controlling the feeding rate to the network, e.g. by controlling the video pump
• CPC Class Codes: H04N 21/2393 involving handling client requests scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04N 21/2401 Monitoring of the client buffer
• CPC Class Codes: H04N 21/2402 Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/440281 by altering the temporal resolution, e.g. by frame skipping television signal recording using magnetic recording on tape for reproducing at a rate different from the recording rate H04N5/783
• CPC Class Codes: H04N 21/6587 Control parameters, e.g. trick play commands, viewpoint selection
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database

Abstract

When a get resource message arrives from an exterior, a resource allocation part reserves a resource. In case of data reading or data writing, a declared value management part checks parameters and a slot allocation part allocates the resource, thereby constructing an efficient file system guaranteeing delay quality in relation to data reading. As the result, it is possible to provide a file system providing pictures in a quick response time for requests from users and supporting users requiring various regeneration speeds.

Claims

1. A server unit connected with a plurality of terminals through wired or wireless transmission paths, said server unit being operable to retrieve and read data stored therein when a data read request is sent from any of the plurality of terminals, and to transmit the read data to any of the terminals issuing the data read request, said server unit comprising:

a data storage part operable to store data, said data storage part being randomly accessible in response to data read requests sent by the terminals;

an input/output part operable to control input/output of the data between said data storage part and each of the plurality of terminals;

an exchange part operable to exchange the data between said input/output part and said data storage part; and

a resource management part operable to manage resources necessary for reading data requested by the terminals from said data storage part and for outputting the resources to the terminals,

wherein said resource management part is operable to separate the resources into preferential resources employed for outputting preferential data for which continuity must be guaranteed to the terminals, and into non-preferential resources employed for outputting non-preferential data for which continuity is not guaranteed to the terminals.

2. The server unit according to claim 1, wherein the plurality of terminals are divided into a plurality of groups, and wherein:

said input/output part comprises a plurality of I/O units provided to each group of terminals,

each of said plurality of I/O units comprises

a preferential input/output control part operable to execute input/output control in accordance with a command requesting reading of the preferential data sent from terminals of a corresponding group, and

a non-preferential input/output control part operable to execute input/output control in accordance with a command requesting reading of the non-preferential data sent from the terminals of the corresponding group;

said data storage part comprises

a plurality of storage units, and

a plurality of MSFSs connected with each of said plurality of storage units, said plurality of MSFS being operable to control reading of data from said plurality of storage units; and

said non-preferential input/output control part comprises

at least one command queue operable to temporarily store commands requesting reading of the non-preferential data sent from the terminals of the corresponding group;

a command queue control part operable to fetch the commands from said command queue;

a command transmission part operable to transmit the commands fetched by said command queue control part to corresponding MSFSs;

a data buffer part operable to temporarily store the non-preferential data read from said plurality of storage units by said MSFSs; and

a data transmission part operable to transmit the non-preferential data stored in said data buffer part to the terminals.

3. The server unit according to claim 2, wherein

each said command queue corresponds to a respective terminal and is operable to store the commands from the respective terminal in order of arrival of the commands, and

said command queue control part is operable to execute a command fetch process which selects a single command queue, fetches a command stored in a head of the command queue, and outputs the fetched command to said command transmission part, and wherein:

said command transmission part is operable to

transmit the commands received from said command queue control part to said MSFSs, and

transmit a received completion notice to said command queue control part when said data buffer part has received all read data for the fetched commands from said MSFSs; and

said command queue control part is operable to repeatedly execute said command fetch process each time the received completion notice is received from said command transmission part.

4. The server unit according to claim 3, wherein said command queue control part limits a number of the commands being fetched from the single command queue to not more than a predetermined constant number in said command fetch process.

5. The server unit according to claim 3, wherein said non-preferential input/output control part further comprises a buffer management part operable to manage a used state of said data buffer part, and

said command queue control part is operable to select the single command queue from among the queues corresponding respectively to the terminals of the group on the basis of a used state of said data buffer part being managed by said buffer management part.

6. The server unit according to claim 5, wherein said buffer management part is provided with a plurality of used quantity counters operable to count a number of untransmitted data stored in said data buffer part for each of the terminals, and

said command queue control part is operable to refer to said used quantity counters of said buffer management part before executing said command fetch process to select a command queue corresponding to one of the terminals having a least number of the untransmitted data as a target of said command fetch process.

7. The server unit according to claim 3, wherein said command transmission part is operable to transmit a command received from said command queue control part to said MSFSs after reserving an area for storing the non-preferential data to be read by said MSFSs in said data buffer part, and to not transmit the commands to said MSFSs if the area cannot be reserved.

8. The server unit according to claim 2, wherein said command queue control part is operable to determine a rate at which to output the commands to said command transmission part based on a load of a communication band serving as a non-preferential resource for outputting data for each of said plurality of I/O units to each of the terminals, and based on a load of a communication band serving as a non-preferential resource for receiving the non-preferential data from said data storage part to each of said plurality of I/O units.

9. The server unit according to claim 2, wherein said command transmission part comprises:

a plurality of transmission queues provided correspondingly to respective MSFSs for storing commands received from said command queue control part for said respective MSFSs; and

a plurality of processing number counters provided correspondingly to said plurality of transmission queues, said processing number counters being incremented for each transmission of the commands from corresponding transmission queues to said MSFSs, and said processing number counters being decremented for each arrival of data read from said corresponding MSFSs to said data buffer part, so as to count the number of the non-preferential data requested for but not yet arrived at said data buffer part, and

said command transmission part being operable to limit a number of the commands being transmitted from said respective transmission queues to said MSFSs so that said a number of unarrived non-preferential data counted by said processing number counters are not in excess of a prescribed threshold.

10. The server unit according to claim 1, wherein said resource management part manages a communication band of said exchange part, a band for said data storage part for reading data, and a communication band for said input/output part for outputting data to respective terminals as the resources.

11. The server unit according to claim 1, wherein said exchange part is formed by an ATM switch, and

a communication band serving as a non-preferential resource of said ATM switch is ensured in an ABR mode.

12. The server unit according to claim 1, wherein said resource management part is operable to fixedly allocate parts of the overall resources of said server unit as the preferential resources while allocating the remaining parts as the non-preferential resources.

13. The server unit according to claim 1, wherein said resource management part is operable to change a quantity being allocated as the preferential resources in response to data read requests for the preferential data received from the terminals.

14. The server unit according to claim 13, wherein said resource management part is operable to allocate all resources which are not already allocated as the preferential resources as the non-preferential resources, and to allocate preferential resources from resources allocated as non-preferential resources in such a range that the quantity of the non-preferential resources is not below a prescribed resource quantity.

15. A file system operable to issue a data acquisition request to a data storage unit in response to a data transmission request from a user, and to transmit data acquired from said data storage unit to the user, said file system comprising:

a data acquisition part operable to successively acquire data from said storage unit in an order of the data being stored in said data storage unit from a position specified continuously by the data transmission request, and at a specified speed;

a buffer operable to store the data acquired by said data acquisition part from said data storage unit;

a buffer management part operable to perform operation of the data stored in said buffer, and to manage a quantity of the data stored in said buffer;

a data transmission part operable to successively read the data stored in said buffer in an order specified by the data transmission request continuously at a specified transmission speed, and to transmit the data to the user; and

a pause control part operable to receive a pause request and a pause release request from the user for controlling said data transmission part, said data acquisition part and said buffer management part, wherein

in response to receiving the pause request from the user, said pause control part is operable to control said data transmission part to immediately stop data transmission while controlling said data acquisition part to immediately stop data acquisition,

in response to receiving the pause release request from the user, said pause control part is operable to control said data transmission part to resume data transmission successively from a head of the data stored in said buffer, and to control said data acquisition part to resume data acquisition successively from data subsequent to a tail of the data stored in said buffer, and

said pause control part is further operable to calculate a data transmission resume time and a data acquisition time at which said data transmission part and said data acquisition part respectively resume data transmission and data acquisition in accordance with a specified pause release transmission speed.

16. The file system according to claim 15, wherein said pause control part is operable to calculate a data transmission resume time tsd at which said data transmission part resumes data transmission in accordance with the expression

17. The file system according to claim 15, wherein said pause control part is operable to calculate a data acquisition resume time trd at which said data acquisition part resumes data transmission in accordance with the expression

18. The file system according to claim 15, wherein said pause control part, upon receiving the pause release request from said user, is operable to:

determine whether or not a quantity of the data being stored in said buffer is greater than a limit that is transmittable at a predetermined data transmission speed after the pause release is received during a time required by said data acquisition part to acquire the data; and

control said buffer management part to delete parts of data exceeding the limit if it is determined that the data quantity is greater than the limit, thereby determining a head position of the data to be next acquired by said data acquisition part after the pause release is received.