fs – file server, dump
The file server was the main file system for Plan 9.
It was a stand-alone system that ran on
a separate computer.
It served the Plan 9 protocol via the IL/IP
protocols on Ethernets.
The name of the main file server at Murray Hill was
The group numbered 9999, normally called
is a simple disk-based file system not backed by the worm.
is a worm-based file system with a disk-based
The disk cache holds
modified worm blocks
to overcome the write-once property of the worm.
The cache also holds recently accessed
non-modified blocks to
speed up the effective access time of the worm.
(usually daily at 5AM) the modified blocks in the
disk cache are
Each time the main file system is dumped,
its root is appended to a subdirectory of the dump file system.
Since the dump file system is not mirrored with a disk
it is read-only.
The name of the newly added root is created from the date
of the dump:
unhandled troff command .sp
The root of the main file system
that is frozen on the first dump
of March 1, 1992
will be named
Place the root of the
9fs dump ls -l /n/dump/1992/02??/mips/bin/vc
To get only one line of output for each version of the compiler:
ls -lp /n/dump/1992/02??/mips/bin/vc | uniq
mount -c /srv/boot /n/emelieother other
For the moment, the file server serves both the old (third edition) and new (fourth edition) versions of 9P, deciding which to serve by sniffing the first packet on each connection.
Required IL, thus now deprecated.