CFS(4)                                                     CFS(4)

     NAME
          cfs - cache file system

     SYNOPSIS
          cfs -s [-dknrS] [-f partition]

          cfs -a netaddr [-dknrS] [-f partition] [mtpt]

          cfs -F srvfile [-dknrS] [-f partition] [mtpt]

     DESCRIPTION
          Cfs is a user-level file server that caches data from remote
          files onto a local disk.  It is normally started by the ker-
          nel at boot time, though users may start it manually.  Cfs
          is interposed between the kernel and a network connection to
          a remote file server to improve the efficiency of access
          across slow network connections such as modem lines.  On
          each open of a file cfs checks the consistency of cached
          information and discards any old information for that file.

          Cfs mounts onto mtpt (default /mnt/cfs) after connecting to
          the file server.

          The options are:

          a netaddr
             dial the destination netaddr to connect to a remote file
             server.  Exclusive with -F.

          d  turn on debugging.

          f partition
             use file partition as the cache disk partition.

          F srvfile
             open srvfile (often a file under /srv) to connect to a
             remote file server.  Exclusive with -a.

          k  keep cache contents even if they might have come from a
             different server.  Cfs will obey -r even if -k is given.

          n  mount the remote file server without authentication;
             often useful with -F.

          r  reformat the cache disk partition.

          s  the connection to the remote file server is on file
             descriptors 0 and 1.

     CFS(4)                                                     CFS(4)

          S  turn on statistics gathering.  A file called cfsctl at
             the root of the caching file system can be read to get
             statistics concerning number of calls/bytes on client and
             server sides and latencies.

          All 9P messages except read, clone, and walk (see intro(5))
          are passed through cfs unchanged to the remote server.  If
          possible, a read is satisfied by cached data.  Otherwise,
          the file server is queried for any missing data.

     FILES
          /dev/sdC0/cache
               Default file used for storing cached data.

     SOURCE
          /sys/src/cmd/cfs