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.
