3 cwfs \- cached-worm file server, dump
23 is a cached-worm file server that runs
24 as a user-mode program and can
25 maintain file systems created by
27 the original Plan 9 file server
28 that had its own kernel and operated
29 a standalone system with disks and
30 optical-disc jukebox attached.
33 which could only accept 9P connections over IL/IPv4 on Ethernets
34 (or over Datakit and Cyclones, long ago),
36 accepts 9P connections over any network medium and protocol
37 that it can announce on,
38 by default TCP (over IPv4 or IPv6).
39 Given suitable 9P clients,
40 one could even run 9P over
47 implements a 16K file system block size
48 and 32-bit disk addresses,
49 in order to be compatible with some existing file systems, notably
51 These parameters can be changed by recompilation.
54 places its server 9P connection in
56 and its command pipe in
57 .BI /srv/ name\f1 .cmd,
67 other than the default
77 use a newer, faster, and incompatible cache-device layout.
78 To convert an old file system's cache to the new layout,
79 dump the file system, note the last superblock number,
87 the file system, and start
94 enter the file server's configuration mode
95 before starting normal operation.
100 name of the file server's configuration.
103 Post file descriptor zero in
105 and read and write protocol messages on file descriptor one.
110 contains a simple device name
113 and a replacement per line.
114 The device name is in the usual
118 The replacement can be the name of an existing file
122 or another such device name.
123 For example, the file
133 would map accesses to device
137 and accesses to device
147 The file server normally requires all users except
149 to provide authentication tickets on each
151 This can be disabled using the
153 configuration command (see
156 The group numbered 9999, normally called
159 on the file server. Any user belonging to that group has
160 attenuated access privileges. Specifically, when checking such
161 a user's access to files, the file's permission bits are first ANDed
162 with 0770 for normal files or 0771 for directories. The effect is
163 to deny world access permissions to
166 when walking directories.
170 is always allowed to attach to
172 without authentication but has minimal permissions.
175 maintains three file systems
176 on a combination of disks and
177 write-once-read-many (WORM) magneto-optical disks.
180 is a simple disk-based file system similar to
184 is a worm-based file system with a disk-based
188 to overcome the write-once property of the worm.
189 The cache also holds recently accessed
190 non-modified blocks to
191 speed up the effective access time of the worm.
193 (usually daily at 5AM) the modified blocks in the
197 traffic to the file system is halted and the
198 modified blocks are relabeled to the unwritten
201 the file system traffic is continued and
202 the relabeled blocks are copied to the worm by
203 a background process.
206 Each time the main file system is dumped,
207 its root is appended to a subdirectory of the dump file system.
208 Since the dump file system is not mirrored with a disk
211 The name of the newly added root is created from the date
213 .BI / yyyy / mmdds\f1.
220 is the day number and
222 is a sequence number if more than
223 one dump is done in a day.
227 For the subsequent dumps
231 The root of the main file system
232 that is frozen on the first dump
236 in the dump file system.
237 .SS "Changes from fs"
239 IP configuration is ignored and the underlying system's is used.
243 commands have been omitted since they (or equivalents) can now be
244 executed directly on the underlying CPU server,
252 Files can be used directly as wren devices by giving
253 a file name rooted at
255 or using double or single quotes. Such a file name
256 can be appended to the
258 device instead of specifying
269 for Marvell SATA disks are not supported; use
271 to map wren devices to appropriate names under
274 The file server kernel seems to have scanned PCI buses
275 in reverse order from the other Plan 9 kernels,
276 so systems with multiple SCSI cards may find controller
279 can be used to compensate for this if you don't want to change
283 The file server kernel's
285 field in NVRAM was overloaded in recent times to hold a
287 key for the CPU hostowner.
290 runs on a CPU kernel,
291 the location of its configuration block must be supplied on the command line.
293 Disk labels are now implemented for
296 At the first access of a side,
298 will attempt to read the label and verify that it has the correct side
299 number and byte order; if either is wrong, it will issue a warning.
300 If the label cannot be read,
302 will attempt to write a new label.
304 Place the root of the
308 and show the modified times of the MIPS C compiler
309 over all dumps in February, 1992:
314 ls -l /n/dump/1992/02??/mips/bin/vc
317 To get only one line of output for each version of the compiler:
320 ls -lp /n/dump/1992/02??/mips/bin/vc | uniq
334 ``A Cached WORM File System'',
336 Software \- Practice and Experience,
341 ``The 64-bit Standalone Plan 9 File Server''
344 the file server serves both the old (9P1) and new (9P2000) versions of 9P,
345 deciding which to serve by sniffing the first packet on each connection.
347 File system block size and disk address size (32- or 64-bit) are fixed
348 at compilation time, and this is not easily changed.