Method and apparatus for limiting allocated data-storage space in a data-storage unit

For use in a data-storage hierachy having a backing store coupled to a front store, each store having a plurality of addressable data-storage spaces, said hierarchy being adapted to be coupled to a host processor for transferring data signals therewith, means for coupling the host processor and said front and back stores together for transferring data signals therebetween;

• the improvement including in combination;
• means for indicating that data is to be written into said front store;
• allocation means coupled to said indicating means for allocating a plurality of allocatable sets of said addressable data-storage spaces in said front store for said data indicated to be written therein, said allocation means also having means indicating that the allocatable unit of said backing store has a given multiple of data-storage spaces equal to the storage capacity of a given number of data-storage spaces in each set of data-storage spaces of said front store;
• means coupled and being responsive to said allocation means for allocating said sets of addressable data-storage spaces and to activate said coupling means to transfer said indicated data into said front store for storage in said allocated sets;
• examining means coupled to said front store for examining said allocated sets of data-storage spaces for determining which of said allocated data-storage spaces in fact received data signals during said indicated data transfer;
• and
• deallocation means coupled to said examining means and to said front store for deallocating all of said data storage paces that in fact did not receive and store data during said indicated data transfer and that were allocated therefor.

In a data-storage hierarchy having a front store and a backing store and adapted to be coupled to a host processor for transferring data signals therewith and having data-transfer means for transferring data signals between said host processor, said front store and said backing store;

• a control data processor coupled to all of said stores and to said data transfer means and being adapted to receive commands from the host processor relating to movement of data in the data-storage hierarchy;
• said backing store having a plurality of backing store addressable allocatable data-storage spaces each of which has a first data-storage capacity;
• said front store having a plurality of front store addressable allocatable data-storage spaces each of which has a second data-storage capacity less than said first data-storage capacity;
• a control store coupled to said control data processor for storing first program indicia for enabling said control data processor to indicate that data is to be stored in said front store in a data-storage operation;
• second program indicia in said control store for enabling said control data processor to allocate a given number of said front store data-storage spaces for storage of data in said front store which in total yields an allocated data-storage capacity of not less than said first data-storage capacity;
• third program indicia in said control store for enabling said control data processor to transfer and store data in said allocated front store data-storage spaces up to said first capacity;
• fourth program indicia in said control store for enabling said control data processor upon completion of the data-storage operation to examine which of the allocated spaces allocated by said second program indicia have in fact received and stored or not received and not stored data as a result of the data-storage operation;
• and
• fifth program indicia in said control store for enabling said control data processor to deallocate those second indicia allocated data-storage spaces of said front store not in fact storing data as a result of the data storage operation whereby the data-storage space of said front store may be more efficiently utilized.