EP0278317A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A system and method for using cached data at a local node after re-opening a file at a remote node in a distributed networking environment
Assignee: International Business Machines Corp
•
Filing: 1988-01-26
•
Granted: —
•
Expires: 2008-01-26
Abstract
Abstract In a distributed environment several data processing systems are interconnected across a network system (3). A distributed services program installed on the systems in the network allows the processors to access data files (5) distributed across the various nodes (A,B) of the network without regard to the location of the data file in the network. The processing system accessing the file, referred to as the client processing system, utilizes a client cache (12B) within its operating system (11B) to store the data file. Utilizing the client cache minimizes the number of reads and writes that must go over the network (3) to the server processing system where the file physically resides. The system and method of this invention prevents a process in the client processing system from accessing data in the client cache that has been modified at another node (A) in the network. The blocks of data in the client cache (12B) are tested for validity in the client processing system by using modification times as measured by the server processing system. If the cache data blocks are determined to be valid, the data is accessed from the client cache. If the cache data blocks are determined to be invalid, the data blocks are discarded, and the file is accessed from the server processing system.
Inventors
- 👤 Albert Chang
- 👤 Amal Ahmed Shaheen-Gouda
- 👤 Grover Herbert Neuman
- 👤 Todd Allen Smith
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 19:34
CPC Classifications
G; G06; G06F; G06F12/00; G06F12/02; G06F12/08; G06F12/0802; G06F12/0806; G06F12/0813; Y; Y10; Y10S; Y10S707/00; Y10S707/99951; Y10S707/99952
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
76 words
A system for accessing a file (5) in a server processing system (10A) at a server node (A) for use by a client processing system (10B) at a client node (B), said system comprising: a client cache (12B) in the client processing system (10B) for buffering a plurality of blocks of the file at the client node (B) from the server processing system; and means for determining the validity of the blocks in the client cache.
Claim 2
Independent Claim
76 words
A system for accessing a file (5) in a server processing system (10A) at a server node (A) for use by a client processing system (10B) at a client node (B), said system comprising: a client cache (12B) in the client processing system (10B) for buffering a plurality of blocks of the file at the client node (B) from the server processing system; and means for determining the validity of the blocks in the client cache.
Claim 3
Dependent Claim
22 words
The system of Claim 1 wherein the client processing system (10B) determines the validity of the blocks in the client cache (12B).
Claim 4
Dependent Claim
23 words
The system of Claim 1 wherein a time at the server processing system (10A) is used to determine the validity of the blocks.
Claim 5
Dependent Claim
26 words
The system of Claim 1 wherein the blocks of the file in the client cache (12B) are accessed if the blocks are determined to be valid.
Claim 6
Dependent Claim
24 words
The system of Claim 1 wherein the file is accessed from the server processing system (10A) if the blocks are determined to be invalid.
Claim 7
Dependent Claim
26 words
The system of Claim 1 wherein the blocks of the file in the client cache (12B) are discarded whenever the blocks are determined to be invalid.
Claim 8
Dependent Claim
109 words
A system of claim 1, wherein said system further comprises; a latest modification time written to the file at the server processing system (10A) whenever the file is changed; a plurality of cache data blocks in the client cache (12B) assigned to the file, said data blocks comprising the latest modification time written to the file at the server processing system when the file is closed at the client processing system; and a surrogate inode (114,150) in the client cache (12B) having the latest modification time written to the file at the server processing system at a time of a first open of the file in the client processing.
Claim 9
Dependent Claim
18 words
The system of Claim 7 wherein the surrogate inode further comprises a file handle (153) identifying the file.
Claim 10
Dependent Claim
21 words
The system of Claim 7 wherein the surrogate inode further comprises means (152) for identifying the server node of the file.
Claim 11
Dependent Claim
18 words
The system of Claim 7 wherein the cache data blocks further comprise a file handle identifying the file.
Claim 12
Dependent Claim
21 words
The system of Claim 7 wherein the cache data blocks further comprise means for identifying the server node of the file.
Claim 13
Independent Claim
57 words
A method for accessing a file (5) in a server processing system (10A) at a server node (A) for use by a client processing system (10B) at a client node (B), said method comprising: buffering the file in a client cache (12B) having data blocks; and determining the validity of the data blocks in the client cache.
Claim 14
Independent Claim
57 words
A method for accessing a file (5) in a server processing system (10A) at a server node (A) for use by a client processing system (10B) at a client node (B), said method comprising: buffering the file in a client cache (12B) having data blocks; and determining the validity of the data blocks in the client cache.
Claim 15
Dependent Claim
20 words
The method of Claim 12 wherein the validity of the data blocks is determined at the server processing system (10A).
Claim 16
Dependent Claim
22 words
The method of Claim 12 wherein the validity of the data blocks is determined by a time at the server processing system.
Claim 17
Dependent Claim
32 words
The method of Claim 12 further comprising the step of accessing data from the client cache (12B) of the client processing system (10B) if the data blocks are determined to be valid.
Claim 18
Dependent Claim
28 words
The method of Claim 12 further comprising the step of accessing the file from the server processing system (10A) if the data blocks are determined to be invalid.
Claim 19
Dependent Claim
27 words
The method of Claim 12 further comprising the step of discarding data in the client cache (12B) block when the data blocks are determined to be invalid.
Claim 20
Dependent Claim
168 words
A method of claim 12 further comprising the steps of: writing a latest modification time to the file at the server processing system (10A) whenever the file is updated; recording the latest modification time in the client processing system (10B) at a time of a first open of the file in the client processing system; allocating a cache block assigned to the file in a client cache (12B) in the client processing system when a block of the file is read; recording the time recorded in the client processing system at the time of the first open in the allocated cache block; updating the time recorded in each allocated cache block assigned to the file at a time of a close of the file at the client processing system with the latest modification time to the file at the server processing system; and comparing the latest modification time recorded in the client processing system at the first open to the latest modification time in the allocated cache block.
Claim 21
Dependent Claim
44 words
The method of Claim 18 further comprising the step of accessing data from the client cache (12B) of the client processing system if the time recorded in the client processing system at the first open is equal to the time in the cache block.
Claim 22
Dependent Claim
43 words
The method of Claim 18 further comprising the step of accessing the file from the server processing system (10A) if the time recorded in the client processing system (10B) at the first open is not equal to the time in the cache block.
Claim 23
Dependent Claim
42 words
The method of Claim 18 further comprising the step of discarding the data in the client cache block if the time recorded in the client processing system (12B) at the first open is not equal to the time in the cache block.
Claim 24
Dependent Claim
46 words
The method of Claim 18 further comprising the step of replacing the data in the cache block with current data from the server if the time recorded in the client processing system at the first open is not equal to the time in the cache block.
Claim 25
Dependent Claim
26 words
The method of Claim 21 wherein the data is discarded at any time the client processing system determines the said compared modification times are not equal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.