Efficient utilization of limited access archival storage in a time shared environment

Abstract

The public storage in any time sharing system tends to continually grow. This necessitates the implementation of certain measures to maintain public storage. One of these possibilities is creation of an archival level of storage called "migrated" storage. Data that have not been referenced recently are moved or "migrated" to a less accessible level of external storage. Since these data are not accessed by the users directly, i. e. , the data must be restored to public storage before being used, a certain variable length coding technique, viz. , Huffman Coding, is used to compact and store these data. The ideas presented have been implemented on a version of TSS/360 Time Sharing System and are presently being used in a real environment. The overall compaction rate achieved was 3. 16 to 1. Further details on compaction rates and timings are also presented.