man(1) Manual page archive

     FS(4)                                                       FS(4)

          fs - file server, bootes


          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 includ-
          ing Datakit/URP, Ethernet IL/IP and Cyclone fiber direct
          connections.  The name of this machine is bootes.

          Bootes can use an external authentication server to validate
          clients.  Because the authentication server itself uses
          bootes as a file server, though, to avoid chicken-and-egg
          problems bootes usually authenticates its own connections.
          Thus when changes are made to the authentication server's
          database it is necessary to run auth (see fs(8)) to update
          bootes's internal state.

          The user none is always allowed to attach to bootes without
          authentication but has minimal permissions.

          Bootes maintains three file systems on a combination of
          disks and write-once-read-many (WORM) magneto-optical disks.

               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 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 dumped. At this time, traffic to
               the file system is halted and the modified blocks are
               relabeled to the un-written 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

          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

     FS(4)                                                       FS(4)

               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.

          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 com-

               ls -lp /n/dump/1992/02??/mips/bin/vc | uniq

          Make the other file system available in directory

               mount -ct /srv/boot /n/bootesother other

          yesterday(1), srv(4), fs(8)
          Sean Quinlan, A Cached WORM File System, Software - Practice
          and Experience, December, 1991