Method for reducing disk I/O accesses in a multi-processor clustered type data processing system
First Claim
1. A method to minimize I/O access operations in a data processing system havingA) a plurality of processor units comprising a first processor unit with a first main memory, first operating systems, and first secondary storage device;
- a second processor unit with a second main memory and second operating system; and
a third processor unit with a third main memory and third operating system; and
B) a switch for selectively interconnecting any pair of said units in a data transferring relationship to permit data that is stored in said first memory to be transferred to said third main memory in response to request from said third unit to said first unit, said method comprising the following steps in combination;
A) maintaining by each said first, second and third operating system,(a) a list of each of the files stored in said data processing system, and(b) an indication of which of said processor units is the access coordinator for said each of said files,B) opening one of said files, stored at said first processor unit as identified by said indication in response to a request to said first processor unit for specified information from said second said processor unit,C) transferring from said first secondary storage device of said first processor unit to said first main memory and thereafter transferring from said first main memory to said second main memory said specified information from said one of said files in response to said request by said second processor unit, and discarding said specified information from said first main memory, andD) thereafter transferring said specified information from said second main memory to said third main memory in response to a request from said first operating system to said second operating system, that was prompted by a request to said first operating system from said third operating system for said specified information.
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Abstract
A method for minimizing I/O mechanical assess operations on secondary storage devices in a data processing system having a plurality of processor units interconnected in a cluster configuration to permit each processor unit to request and obtain data that is resident only on a secondary storage device of one processor unit. The method involves the steps of maintaining at each processor unit information about each copy of data that has been sent from the unit to another unit to permit a second request to the unit to be serviced by transferring a copy of the data from the main memory which is storing the data to the requesting unit rather than servicing the request with a relatively slow I/O accessing operation to a secondary storage device.
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Citations
9 Claims
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1. A method to minimize I/O access operations in a data processing system having
A) a plurality of processor units comprising a first processor unit with a first main memory, first operating systems, and first secondary storage device; - a second processor unit with a second main memory and second operating system; and
a third processor unit with a third main memory and third operating system; andB) a switch for selectively interconnecting any pair of said units in a data transferring relationship to permit data that is stored in said first memory to be transferred to said third main memory in response to request from said third unit to said first unit, said method comprising the following steps in combination; A) maintaining by each said first, second and third operating system, (a) a list of each of the files stored in said data processing system, and (b) an indication of which of said processor units is the access coordinator for said each of said files, B) opening one of said files, stored at said first processor unit as identified by said indication in response to a request to said first processor unit for specified information from said second said processor unit, C) transferring from said first secondary storage device of said first processor unit to said first main memory and thereafter transferring from said first main memory to said second main memory said specified information from said one of said files in response to said request by said second processor unit, and discarding said specified information from said first main memory, and D) thereafter transferring said specified information from said second main memory to said third main memory in response to a request from said first operating system to said second operating system, that was prompted by a request to said first operating system from said third operating system for said specified information. - View Dependent Claims (2, 3, 4)
- a second processor unit with a second main memory and second operating system; and
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5. A method in a data processing system having
a first processor unit with a first main memory, first operating system, and first secondary storage device; - a second processor unit with a second main memory and second operating system; and
a third processor unit with a third main memory and third operating system, said first, second, and third processing units being interconnected by a communication link, said method comprising the following steps;A) maintaining by each said first, second, and third operating system indications of which of said processor units coordinates access for a file in the data processing system; B) maintaining by said first operating system information which indicates that a copy of said file is currently maintained in said second main memory and is not currently maintained in said first main memory, and C) servicing a request by said third processor unit to said first processor unit for a copy of said file, said request being directed to said first processor unit by one of said indications indicating at said third processor unit that said first processor unit coordinates access to the identified data, said servicing causing said second processor unit to transfer a copy of said file to said third main memory, rather than said first unit servicing said request by an I/O operation to said first secondary storage device if said file is not in said first main memory. - View Dependent Claims (6, 7, 8, 9)
- a second processor unit with a second main memory and second operating system; and
Specification