3 fs \- file server, dump
7 The file server was the main file system for Plan 9.
8 It was a stand-alone system that ran on
10 It served the Plan 9 protocol via the IL/IP
11 protocols on Ethernets.
12 The name of the main file server at Murray Hill was
15 The file server normally requires all users except
17 to provide authentication tickets on each
19 This can be disabled using the
21 configuration command (see
24 The group numbered 9999, normally called
27 on the file server. Any user belonging to that group has
28 attenuated access privileges. Specifically, when checking such
29 a user's access to files, the file's permission bits are first ANDed
30 with 0770 for normal files or 0771 for directories. The effect is
31 to deny world access permissions to
34 when walking directories.
38 is always allowed to attach to
40 without authentication but has minimal permissions.
43 maintains three file systems
44 on a combination of disks and
45 write-once-read-many (WORM) magneto-optical disks.
48 is a simple disk-based file system not backed by
52 is a worm-based file system with a disk-based
56 to overcome the write-once property of the worm.
57 The cache also holds recently accessed
58 non-modified blocks to
59 speed up the effective access time of the worm.
61 (usually daily at 5AM) the modified blocks in the
65 traffic to the file system is halted and the
66 modified blocks are relabeled to the unwritten
69 the file system traffic is continued and
70 the relabeled blocks are copied to the worm by
74 Each time the main file system is dumped,
75 its root is appended to a subdirectory of the dump file system.
76 Since the dump file system is not mirrored with a disk
79 The name of the newly added root is created from the date
81 .BI / yyyy / mmdds\f1.
90 is a sequence number if more than
91 one dump is done in a day.
95 For the subsequent dumps
99 The root of the main file system
100 that is frozen on the first dump
104 in the dump file system.
106 Place the root of the
110 and show the modified times of the MIPS C compiler
111 over all dumps in February, 1992:
115 ls -l /n/dump/1992/02??/mips/bin/vc
118 To get only one line of output for each version of the compiler:
121 ls -lp /n/dump/1992/02??/mips/bin/vc | uniq
126 file system available in directory
130 mount -c /srv/boot /n/emelieother other
141 ``A Cached WORM File System'',
143 Software \- Practice and Experience,
146 For the moment, the file server serves both the old (third edition) and new (fourth
147 edition) versions of 9P, deciding which to serve by sniffing the first packet on each
150 Required IL, thus now deprecated.