In SCAN or second phase (steps from 2b to 2c), it verifies if final object's scores are not duplicate; then, it executes a
sequential access for each list [S.sub.i], and stops when a different score is found in each list.
To recoup the added cost of a disk library, it should deliver high enough
sequential access to replace ten or more tape drives.
Host Data Connect already supported the main IMS database organizations - HISAM (Hierarchical Indexed
Sequential Access Method), HIDAM (Hierarchical Indexed Direct Access Method), HDAM (Hierarchical Direct Access Method), SHISAM (Simple Hierarchical Indexed
Sequential Access Method), HSAM (Hierarchical
Sequential Access Method) and SHSAM (Simple Hierarchical
Sequential Access Method).
It may be noted that a
sequential access to semantic and phonological information is a frequent feature of current models of speech production.
A
sequential access stream resulting from a tight loop, for example, may not allow sufficient lead time between the use of block b and the request for block b + 1.
Of portability I will have more to say later, but we all access information in books randomly by riffling their pages (which is why we prefer books over the "
sequential access" of microfilm), and publishers assist us in this activity with tables of contents, indexes, running heads, chapter titles and subheadings.
RBASE and dBASE have a behavior similar to COBOL where
sequential access without indices is much faster.
Using iSMART's disk usage information, such as read/write, random and
sequential access, and block sizes, users will also be able to verify that they bought the ideal product for their specific application, fine tune software settings for better performance, and even save money by ensuring that they choose the most suitable drives for their applications in the future.
Some architectural issues remain facing traditional tape storage and include: 1) the time to first byte of data (milliseconds for disk and seconds for tape); 2) tape supports
sequential access only (disk supports random and
sequential access); and 3) the recovery time for data is longer for tape than for mirrored or replicated disk (minutes or hours on tape compared to seconds normally for mirrored disk).