term% cat index.txt FS(4) Kernel Interfaces Manual FS(4)
NAME
fs - file server, dump
SYNOPSIS
none
DESCRIPTION
The file server is the main file system for Plan 9. It is a stand-
alone system that runs on a separate computer. It serves the Plan 9
protocol on a variety of networks including Datakit/URP, Ethernet IL/IP
and Cyclone fiber direct connections. The name of the main file server
at Murray Hill is bootes.
The file server normally requires all users except to provide authenti‐
cation tickets on each attach(5). This can be disabled using the
noauth configuration command (see fsconfig(8)).
The user none is always allowed to attach to bootes without authentica‐
tion but has minimal permissions.
Bootes maintains three file systems on a combination of disks and
write-once-read-many (WORM) magneto-optical disks.
other is a simple disk-based file system similar to kfs(4).
main is a worm-based file system with a disk-based look-aside cache.
The disk cache holds modified worm blocks to overcome the write-
once property of the worm. The cache also holds recently ac‐
cessed non-modified blocks to speed up the effective access time
of the worm. Occasionally (usually daily at 5AM) the modified
blocks in the disk cache are dumped. At this time, traffic to
the file system is halted and the modified blocks are relabeled
to the unwritten portion of the worm. After the dump, the file
system traffic is continued and the relabeled blocks are copied
to the worm by a background process.
dump 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 cache, it is read-only. The
name of the newly added root is created from the date of the
dump: /yyyy/mmdds. Here yyyy is the full year, mm is the month
number, dd is the day number and s is a sequence number if more
than one dump is done in a day. For the first dump, s is null.
For the subsequent dumps s is 1, 2, 3, etc.
The root of the main file system that is frozen on the first
dump of March 1, 1992 will be named /1992/0301/ in the dump file
system.
EXAMPLES
Place the root of the dump file system on /n/dump and show the modified
times of the MIPS C compiler over all dumps in February, 1992:
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
Make the other file system available in directory /n/bootesother:
mount -c /srv/boot /n/bootesother other
SOURCE
/sys/src/fs
SEE ALSO
yesterday(1), srv(4), fs(8)
Sean Quinlan, ``A Cached WORM File System'', Software - Practice and
Experience, December, 1991
FS(4)