Data lock management in a distributed file server system determines variable lock lifetime in response to request to access data object
First Claim
1. A method of data management in a distributed file system having a file server adapted to store a plurality of data objects and respond to requests for read and write access to the data objects by granting and terminating data locks to the server-stored data objects, the system further having a plurality of interactive workstations that are adapted to operate in an active mode and in an idle mode, each workstation having a local cache memory;
- the method comprising the steps of;
receiving a request from a first workstation for read or write access to a data object;
determining an appropriate variable lock lifetime that expires in a range from zero to infinity seconds after grant, in response to the received request for access;
granting the first workstation a lock to the data object, the lock having the determined lock lifetime; and
terminating the lock when the lock lifetime expires.
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Accused Products
Abstract
In a distributed file system having a plurality of file servers each associated with a plurality of workstations having cache memories, data locks granted by the file servers to the workstations have variable lock lifetimes that are selected based on system parameters. The parameters selected to determine lock lifetimes can be either statically determined, in which case system operating parameters such as read/write ratio for data objects are assumed, or can be dynamically determined, in which case real-time system operating parameters such as current read/write ratios are used to determine the appropriate lock lifetime.
116 Citations
19 Claims
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1. A method of data management in a distributed file system having a file server adapted to store a plurality of data objects and respond to requests for read and write access to the data objects by granting and terminating data locks to the server-stored data objects, the system further having a plurality of interactive workstations that are adapted to operate in an active mode and in an idle mode, each workstation having a local cache memory;
- the method comprising the steps of;
receiving a request from a first workstation for read or write access to a data object; determining an appropriate variable lock lifetime that expires in a range from zero to infinity seconds after grant, in response to the received request for access; granting the first workstation a lock to the data object, the lock having the determined lock lifetime; and terminating the lock when the lock lifetime expires. - View Dependent Claims (2, 3, 4, 5)
- the method comprising the steps of;
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6. In a system having a file server storing a plurality of data objects and a plurality of interactive workstations accessing the server over a network, the server responding to requests for read and write access to the data objects from different workstations by granting and terminating data locks to the server-stored data objects, each workstation having a local cache and means for communicating access requests and the like to the server, each workstation adapted to operate in an active mode and an idle mode, a method for dynamically managing requests for access to the data objects comprising the steps of:
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(a) responding to a request from a first workstation for access to a server-stored data object by either determining a variable lifetime for a lock and granting a first time-limited lock having the determined variable lifetime to the first workstation in the absence of contention among requests for access, or resolving contention among the requests by identifying a winning request and repeating step (a); (b) responding to a request from a second workstation for access to the data object after the first time-limited lock has been granted to the first workstation, by either deferring the second station request for later resolution if the first station is in the idle mode, or suspending the second station request until the current lock expires if the first workstation is in the active mode, the first workstation resolving a deferred second station request that is valid only within its time duration lock by either granting or denying access to the second workstation; and (c) responding to a request from the first workstation for a second lock on the data object requested during the pendency of the first time-limited lock by repeating step (a). - View Dependent Claims (7, 8, 9, 10)
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11. A distributed file computing system having a central processor connected to a plurality of file servers adapted to store a plurality of data objects and respond to requests for read and write access to the data objects by granting and terminating data locks to the server-stored data objects, each of the file servers being connected to a plurality of client workstations that request access to the data objects and are adapted to operate in an active mode and an idle mode, each workstation having a local cache memory;
- wherein;
the file servers grant data locks having variable lifetimes in a range from zero seconds to infinity seconds, the particular lock lifetime for a requested data object being determined in response to a request for access as a function of at least one of the system read/write ratio, file access rate, the number of workstations served by a file server, number of workstations sharing the data object, the type of request for access, the type of data object for which access is requested, or the type of workstation requesting access. - View Dependent Claims (12, 13, 14)
- wherein;
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15. A program product data storage device, tangibly embodying a program of machine-readable instructions executable by a computer to perform method steps for managing a distributed file system having a file server adapted to store a plurality of data objects and respond to requests for read and write access to the data objects by granting and terminating data locks to the file server-stored data objects, the distributed file system further having a plurality of interactive workstations that are adapted to operate in an active mode and in an idle mode, each workstation having a local cache memory;
- the method steps performed by the computer comprising the steps of;
receiving a request from a first workstation for read or write access to a data object; determining an appropriate variable lock lifetime that expires in a range from zero to infinity seconds after grant, in response to the received request for access; granting the first workstation a lock to the data object, the lock having the determined lock lifetime; and terminating the lock when the lock lifetime expires. - View Dependent Claims (16, 17, 18, 19)
- the method steps performed by the computer comprising the steps of;
Specification