from
The Free On-line Dictionary of Computing (8 July 2008)
New Storage System
<storage> (NSS) A major {Multics} implementation project
during the 1970s. The initial Multics {file system} design
had evolved from the one-huge-disk world of {CTSS}. When
multiple disk units were used they were just assigned
increasing ranges of disk addresses, so a {segment} could have
{pages} scattered over all disks on the system. This provided
good {I/O} {parallelism} but made {crash recovery} expensive.
NSS redesigned the lower levels of the file system,
introducing the concepts of {logical volume} and {physical
volume} and a mapping from a Multics directory branch to a
{VTOC} entry for each file. The new system had much better
recovery performance in exchange for a small space and
performance cost.
(1997-01-29)