Abstract: A computer implemented method for robustly copying pages to system managed storage in order to maintain data in a consistent state and in order to provide continuous access availability of the pages to executing applications. The method achieves data consistency by atomically shadow copying application referenced pages and amending directories in a failure independent medium on (1) an access path interrupt as well as on (2) a page update basis. Availability is enhanced by duplexing the pages and directories as part of the atomic shadow copying step.

Abstract: A method and apparatus for providing non-privileged state cross-memory communications between application programs in disjoint communication memory domains. Appropriate operating systems store a table indicating which communication memory domains and which operations are permitted by a corresponding application program in a corresponding communication memory domain.

Abstract: A method for managing space re-use with respect to the indices (nodes) of shadow written tree organized dynamic random accessed files/records/pages located in the external store of a CPU. The method reserves space in all non-leaf nodes and maintains a list of available node addresses. When a new node is required then space, if available, is obtained from the parent node list. Only when the parent list becomes exhausted is space (node) obtained from a node inventory manager. Deletion of a node causes its address to be placed on the free or available list maintained by that node's parent. If there is no space, then space on the parent node list is obtained by returning to the inventory manager that node on the list having the least locality with the existing subordinate (children) nodes of the parent.

Abstract: A conditional broadcast or notification facility of a global lock manager is utilized to both serialize access to pages stored in local caches of counterpart processors in a distributed system and to ensure consistency among pages common to the caches. Exclusive use locks are obtained in advance of all write operations. When a page is to be updated, which page is cached in a processor other than that of the requester, then a delay is posed to the grant of the exclusive lock, all shared use lock holders to the same page notified, local copies are invalidated, exclusive lock granted, page is updated and written through cache, after which the lock is demoted to shared use.

Abstract: A computer-implemented method for the name-oriented accessing of files having at least zero records, any access path to files and records through an external store coupling the computer being defined by a pair of related directories. A first directory of record entries is sorted on a two-part token. The token consists of a unique sequence number assigned to the record and the sequence number of any parent record entry. Each record entry includes the token, file or record name, and external store address or pointer A traverse through the tokens constitutes a leaf-searchable B-tree.Rapid access to target records is by way of a name-sorted, inverted directory of names and tokens as a subset and which is reconstitutable from the first directory in the event of unavailability.

Abstract: A method for allowing weak-searchers of a B+-tree avoid locks that serialize access to the B+-tree structure. The update technique used to achieve this ensures that the B+-tree is always in a correct state on secondary storage so that repair is not necessary after a system failure. The assumption is made that the readers will complete their reading within a specified period but sometimes will need to be restarted because they have not completed their reading within a predetermined time period.

Abstract: A method to manage the access of data or pages mapped into a very large virtual external address space through a cache without disturbing the logical view of the data and without having to assign physical or real backing store to said logical view. A data cache is used in which pages are indexed according to a logical address intermediate to their virtual address and their physical location in external storage. Pages common to two or more files are updated in place in the cache, while pages bound to only one file are shadow copied.

Abstract: A data cache in a computer operating system that dynamically adapts its size in response to competing demands for processor storage, and exploits the storage cooperatively with other operating system components. An arbiter is used to determine the appropriate size of the cache based upon competing demands for memory. The arbiter is entered cyclically and samples user's wait states. The arbiter then makes a decision to decrease or increase the size of the cache in accordance with predetermined parameters.