Method and apparatus for limiting data occupancy in a cache
First Claim
1. The method of operation a data storage hierarchy coupled to user units and having a backing store and a caching buffer store with means to store data in said buffer store based upon addressable storage areas of said backing store, both of said stores having a plurality of addressable storage areas;
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monitoring chained requests for access to said storage hierarchy received from said units;
setting a status bit based upon monitoring a predetermined type of said chained requests for access which indicates whether or not writing operations for the storage of data are included in the monitored chained requests; and
storing such written data in said backing store when said status bit has been set; and
removing data stored in said buffer store related to said written data from said buffer store whenever said status bit indicates a one of said given writing operations.
1 Assignment
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Accused Products
Abstract
A storage hierarchy has a backing store and a caching buffer store. During a series of accesses to the hierarchy by a user, writing data to the hierarchy results in data being selectively removed from the buffer store. Space in said buffer store not being allocated to data being written results in such data being written to the backing store to the exclusion of the buffer store. Removal of data increases the probability of writing data to the backing store. In a preferred implementation, the backing store is one or more disk type data storage apparatus and the buffer store is an electronic random access memory.
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Citations
35 Claims
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1. The method of operation a data storage hierarchy coupled to user units and having a backing store and a caching buffer store with means to store data in said buffer store based upon addressable storage areas of said backing store, both of said stores having a plurality of addressable storage areas;
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including the steps of; monitoring chained requests for access to said storage hierarchy received from said units; setting a status bit based upon monitoring a predetermined type of said chained requests for access which indicates whether or not writing operations for the storage of data are included in the monitored chained requests; and storing such written data in said backing store when said status bit has been set; and removing data stored in said buffer store related to said written data from said buffer store whenever said status bit indicates a one of said given writing operations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. The method of operating a data storage hierarchy having a backing store and a caching buffer store with means to store data in said buffer store based upon addressable storage areas of said backing store, both of said stores having a plurality of addressable storage areas;
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including the steps of; receiving data storage access requests from a user for reading and writing data from and to the storage hierarchy, respectively; analyzing said writing data access requests, removing data from said buffer store in accordance with said write data analyzing; and analyzing said read data access requests, moving data to said buffer store from said backing store in accordance with said read data analyzing whereby read requests tend to relate to data stored in said buffer store and write requests tend to relate to data stored only in said backing store. - View Dependent Claims (14)
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15. The method of operating a data storage hierarchy having a backing store and a caching buffer store with means to store data in said buffer store based upon addressable storage areas of said backing store, both of said stores having a plurality of addressable storage areas;
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including the steps of; receiving data from a user to be written into said hierarchy at a given addressed area of said backing store; examining said buffer store to determine whether or not an addressable area thereof has been allocated to said given addressed area of said backing store; when said examining reveals an allocated addressable area, write said data in said buffer store to said allocated area; when said examining reveals no allocated addressable area in said buffer relating to said given addressed area, write said data to said given addressed area; monitoring each said write operation and setting a status bit indicating a predetermined one of said write operations, removing predetermined data stored in said buffer store to thereby increase writing data to said backing store; receiving requests from said user for data stored in said storage hierarchy; and moving data to said buffer store from said backing store in accordance with said received requests such that such requests for data tend to be responded to by supplying data to said user from said buffer store. - View Dependent Claims (16, 17, 18)
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19. A data storage hierarchy having an adapter adapted to be connected to using units, comprising:
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a cache store; a backing store connected to said cache store; communication paths connected to said adapter, said backing store and said cache for transferring data signals between said adapter, backing store and cache; switching means coupled to said communications paths for selectively switching the communication paths between said adapter, said backing store, and said cache; read hit means coupled to said communication paths for being responsive to predetermined ones of said data transfers from said cache to said adapter for promoting data from said backing store to said cache store to make said promoted data more readily available to said adapter; directory means coupled to said cache and backing store for indicating data stored in said cache store as it relates to addressable areas of said backing store; means coupled to said communications paths for monitoring writing operations which transfer data signals from said adapter to either said cache or backing store; and means for erasing data within said backing store from said cache for limiting the contents of said cache store in response to said monitoring of said writing operations. - View Dependent Claims (20, 21, 22, 23)
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24. The machine-implemented method of operating a peripheral data storage hierarchy coupled to a host processor for transferring data therewith in accordance with access requests received from said host processor and having a backing store and a buffer store with means to store data in said buffer store based upon addressable storage areas of said backing store, both of said stores have a plurality of addressable data storage areas;
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including the automatic steps of; monitoring a series of requests for access to said storage hierarchy received from said host processor and setting a status bit for indicating whether or not sequential data is being transferred; analyzing said series of requests for predetermined writing and reading access characteristics; promoting all of the data stored in a one of said data storage areas of said backing store having a predetermined address relationship to said analyzed series of requests to said buffer store when said predetermined reading access characteristics occur simultaneously to said sequential data indication; if said indication does not indicate said sequential data transfer, inhibiting promotion of data stored in said one data storage area to said buffer store; and deleting data from said cache having a predetermined relationship to said writing operations.
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25. A data-storage hierarchy adapted to be connected to a using unit and having a backing store with a first plurality of addressable data storage areas and a buffer store with a second plurality of addressable data storage areas, data transfers means connected to said backing store and said buffer store and adapted to be connected to said using unit for transferring data signals therebetween, a digital processor connected to said backing store, said buffer store and said data transfer means to actuate said data transfer means for operating said data transfer means and said stores, said digital processor including stored program means for storing a plurality of control programs, said programs including in combination:
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buffer access program means for enabling said digital processor to actuate said data transfer means for storing and fetching data in and from said buffer store based upon addresses of said addressable data storage areas of said backing store; first program means for enabling said digital processor to monitor a series of requests for access to said storage hierarchy received from said using unit and for setting a status bit to indicate whether or not given data transfer operations occurred within said series of requests that wrote data received from said using unit into said data storage hierarchy; and second program means for enabling said digital processor during any of said series of requests for access, which include writing data to said storage hierarchy, to actuate said data transfer means for storing such written data in said backing store, and for effectively removing predetermined data stored in said buffer store, related to said written data, from said buffer store whenever said indications indicate said given operation. - View Dependent Claims (26)
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27. The method of operating a data storage hierarchy coupled to user units and having a backing store and a caching buffer store with means to store data in said buffer store based upon addressable storage areas of said backing store, both of said stores having a plurality of addressable data storage areas;
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including the steps of; monitoring chained requests received from said units for access to said storage hierarchy; setting a status bit based on receiving a specific one of said monitored requests for access in said chained requests which indicates whether or not specific writing operations for the storage of data in the data storage hierarchy are included in said chained requests; and removing data stored in said buffer store related to said data to be stored when said status bit has been set; and storing said data in said backing store. - View Dependent Claims (28, 29, 30, 31)
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32. The method of operating a data storage hierarchy having an adaptor for being connected to user units for a backing store and a caching buffer store with means to store data in said buffer store based upon addressable storage areas of said backing store, both of said stores having a plurality of addressable data storage areas;
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including the steps of; receiving chained data storage access requests from the adaptor for reading the writing data from and to the storage hierarchy with respect to the user units, respectively; analyzing said received chained data storage access request for a writing data operation access request within such chained data storage; removing data from said buffer store in accordance with the address in said backing store of the data to be written received during said analyzed writing data operation; storing the data received with the write operation request only in said backing store; and analyzing said chained data storage access requests for a read operation; moving data to said buffer store from said backing store in accordance with the address in said backing store of the data to be accessed by the read operation request analyzed; whereby read requests tend to be directed to said buffer store and write requests tend to be directed only to said backing store. - View Dependent Claims (33, 34)
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35. In the method of operating a data storage hierarchy connected to user units and having a backing store and a caching buffer store with means to store data in said buffer store based upon addressable storage areas of said backing store, both of said stores having a plurality of addressable storage areas;
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including the steps of; receiving chained data storage access requests from the user units for reading and writing data from and to the storage hierarchy, respectively; receiving data from the user units to be written into said data storage hierarchy at a given addressed area of said backing store, said address being included with said receiving chained data storage write access request; examining said buffer store to determine whether or not an addressable area thereof has been allocated to said given addressed area of said backing store; when said examined buffer store area reveals an allocated addressable area, writing said data in said buffer store to said allocated area, otherwise writing said data to said given addressed area; monitoring chained requests for access to said storage hierarchy received from said units; setting a status bit based on a monitored specific request for access from said chained requests which indicates whether or not specific writing operations for the storage of data are included in the specific chained request; removing data stored in said buffer store related to said data when said status bit has been set; and storing said received data only in said backing store; receiving requests from said user units for retrieving data stored in said storage hierarchy; and moving data to said buffer store from said backing store in accordance with said received retrieve requests such that said received retrieve requests for data tend to be responded to by supplying data to said user units from said buffer store.
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Specification