METHOD AND SYSTEM FOR HANDLING SEQUENTIAL DATA IN A HIERARCHICAL STORE

摘要

The efficient promotion of data from a backing store (disk storage apparatus 16-18 termed DASD) to a random access cache 40 in a storage systm such as used for swap and paging data transfers. When a sequential access indicator (SEQ in 22) is sent to and retained in the storage system, all data specified in a subsequent read <<paging mode>> command is fetched to the cache from DASD. If such prefetched data is replaced from cache and the sequential bit is on, a subsequent host access request for such data causes all related data not yet read to be promoted to cache. A maximal amount only of related data may be promoted; such maximal amount is determined by cache addressing characteristics and DASD access delay boundaries. Without the sequential bit on, only the addressed data block is promoted to cache.