.TH FS 4.SH NAMEfs \- file server, dump.SH SYNOPSIS.I none.SH DESCRIPTIONThe file server was the main file system for Plan 9.It was a stand-alone system that ran ona separate computer.It served the Plan 9 protocol via the IL/IPprotocols on Ethernets.The name of the main file server at Murray Hill was.BR emelie ..PPThe file server normally requires all users except.L noneto provide authentication tickets on each.IR attach (5).This can be disabled using the.B noauthconfiguration command (see.IR fsconfig (8))..PPThe group numbered 9999, normally called.BR noworld ,is specialon the file server. Any user belonging to that group hasattenuated access privileges. Specifically, when checking sucha user's access to files, the file's permission bits are first ANDedwith 0770 for normal files or 0771 for directories. The effect isto deny world access permissions to.B noworldusers, exceptwhen walking directories..PPThe user.B noneis always allowed to attach to.B emeliewithout authentication but has minimal permissions..PP.B Emeliemaintains three file systemson a combination of disks andwrite-once-read-many (WORM) magneto-optical disks..TP.B otheris a simple disk-based file system similar to.IR kfs (4) ..TP.B mainis a worm-based file system with a disk-basedlook-aside cache.The disk cache holdsmodified worm blocksto overcome the write-once property of the worm.The cache also holds recently accessednon-modified blocks tospeed up the effective access time of the worm.Occasionally(usually daily at 5AM) the modified blocks in thedisk cache are.IR dumped .At this time,traffic to the file system is halted and themodified blocks are relabeled to the unwrittenportion of the worm.After the dump,the file system traffic is continued andthe relabeled blocks are copied to the worm bya background process..TP.B dumpEach 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 diskcache,it is read-only.The name of the newly added root is created from the dateof the dump:.BI / yyyy / mmdds\f1.Here.I yyyyis the full year,.I mmis the month number,.I ddis the day number and.I sis a sequence number if more thanone dump is done in a day.For the first dump,.I sis null.For the subsequent dumps.I sis 1, 2, 3, etc..spThe root of the main file systemthat is frozen on the first dumpof March 1, 1992will be named.B /1992/0301/in the dump file system..SH EXAMPLESPlace the root of the.B dumpfile system on.B /n/dumpand show the modified times of the MIPS C compilerover all dumps in February, 1992:.IP.EX9fs dumpls -l /n/dump/1992/02??/mips/bin/vc.EE.PPTo get only one line of output for each version of the compiler:.IP.EXls -lp /n/dump/1992/02??/mips/bin/vc | uniq.EE.PPMake the.B otherfile system available in directory.BR /n/emelieother :.IP.EXmount -c /srv/boot /n/emelieother other.EE.SH SOURCE.B /sys/src/fs.SH SEE ALSO.IR yesterday (1),.IR cwfs (4),.IR srv (4),.IR fs (8).brSean Quinlan,``A Cached WORM File System'',.ISoftware \- Practice and Experience,December, 1991.SH BUGSFor the moment, the file server serves both the old (third edition) and new (fourthedition) versions of 9P, deciding which to serve by sniffing the first packet on eachconnection..PPRequired IL, thus now deprecated.
.TH FS 4
.SH NAME
fs \- file server, dump
.SH SYNOPSIS
.I none
.SH DESCRIPTION
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
.BR emelie .
.PP
The file server normally requires all users except
.L none
to provide authentication tickets on each
.IR attach (5).
This can be disabled using the
.B noauth
configuration command (see
.IR fsconfig (8)).
.PP
The group numbered 9999, normally called
.BR noworld ,
is special
on the file server. Any user belonging to that group has
attenuated access privileges. Specifically, when checking such
a user's access to files, the file's permission bits are first ANDed
with 0770 for normal files or 0771 for directories. The effect is
to deny world access permissions to
.B noworld
users, except
when walking directories.
.PP
The user
.B none
is always allowed to attach to
.B emelie
without authentication but has minimal permissions.
.PP
.B Emelie
maintains three file systems
on a combination of disks and
write-once-read-many (WORM) magneto-optical disks.
.TP
.B other
is a simple disk-based file system similar to
.IR kfs (4) .
.TP
.B 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 accessed
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
.IR 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.
.TP
.B 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:
.BI / yyyy / mmdds\f1.
Here
.I yyyy
is the full year,
.I mm
is the month number,
.I dd
is the day number and
.I s
is a sequence number if more than
one dump is done in a day.
For the first dump,
.I s
is null.
For the subsequent dumps
.I s
is 1, 2, 3, etc.
.sp
The root of the main file system
that is frozen on the first dump
of March 1, 1992
will be named
.B /1992/0301/
in the dump file system.
.SH EXAMPLES
Place the root of the
.B dump
file system on
.B /n/dump
and show the modified times of the MIPS C compiler
over all dumps in February, 1992:
.IP
.EX
9fs dump
ls -l /n/dump/1992/02??/mips/bin/vc
.EE
.PP
To get only one line of output for each version of the compiler:
.IP
.EX
ls -lp /n/dump/1992/02??/mips/bin/vc | uniq
.EE
.PP
Make the
.B other
file system available in directory
.BR /n/emelieother :
.IP
.EX
mount -c /srv/boot /n/emelieother other
.EE
.SH SOURCE
.B /sys/src/fs
.SH SEE ALSO
.IR yesterday (1),
.IR cwfs (4),
.IR srv (4),
.IR fs (8)
.br
Sean Quinlan,
``A Cached WORM File System'',
.I
Software \- Practice and Experience,
December, 1991
.SH BUGS
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.
.PP
Required IL, thus now deprecated.