| 摘要 |
Described is a storage control system for a two-level storage system. The system includes a high-speed storage against which requests for data are processed and a slower, larger-capacity main storage. Requests for data are received in terms of logical addresses. Requests can be received concurrently at a plurality of request ports where they are buffered in request stacks. A tag storage serves as an index to the data currently resident in high-speed storage, and a directory storage acts as an index to data currently in main storage. A sequence interlock generator is included which interlocks requests in the plurality of request stacks to insure that requests to the same storage area are performed in proper sequence to insure data integrity. When a request is serviced, the logical address is transformed into a plurality of physical addresses in high-speed storage. The corresponding tags from the tag storage and the corresponding data from the high-speed storage are concurrently fetched. A comparison is made of the tags with the transformed address to determine whether the requested data is in high-speed storage. Since request to the same storage entity in high-speed storage or tag storage can be made concurrently by all request ports, conflict resolvers are included to resolve conflicts arising from simultaneous requests to either of these two storages. High-speed storage is divided into storage modules capable of simultaneous operation such that requests from the plurality of request ports can be serviced concurrently. If comparison of the tags indicate that the requested data is available, the request is serviced. An interstorage transfer mechanism is included such that if the requested data is not available in high-speed storage, then the data is retrieved from main storage and placed into high-speed storage for subsequent processing of the request. Concurrently with interstorage transfer, processing of other requests from the request ports is permissible. In the replacement of data from main storage to high-speed storage, provision is made for also replacing data from high-speed storage to main storage if such be necessary.
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