fms(8)

NAME

   fms - Determine a tape's capacity and a tape device's filemark size

SYNOPSIS

   fms -tape <tape special file> [-help]

   fms -t <tape special file> [-h]

DESCRIPTION

   The fms command determines the capacity of the tape currently in the
   tape device identified by the -tape argument, along with the size of
   the filemark for the device. The filemark is also referred to as the
   device's end-of-file (EOF) marker, and can differ for each combination
   of tape and tape device.

   As the Tape Coordinator writes a dump, it writes a filemark between the
   data included from each volume and also tracks the amount of space left
   before the end of the tape (EOT). For some tape devices, the filemark
   is large enough (multiple megabytes) that failure to consider it leads
   the Tape Coordinator significantly to overestimate the available space.

   The intended use of this command is to determine tape capacity and
   filemark size values that can be specified in a tape device's entry in
   the /var/lib/openafs/backup/tapeconfig file. For certain types of tape
   drives, the Tape Coordinator operates more efficiently when the
   tapeconfig file lists accurate values. For further discussion, see the
   OpenAFS Administration Guide chapter on configuring the Backup System.

   Insert a tape in the drive before issuing this command.

CAUTIONS

   Do not use this command on compressing tape devices in compression mode
   or with tape devices that handle tapes of multigigabyte (or
   multiterabyte) capacity. It does not produce accurate results in those
   cases.  For alternate suggestions on the values to record in the
   tapeconfig file for compressing drives, see the OpenAFS Administration
   Guide chapter on configuring the Backup System.

   Running the command completely overwrites the tape, so use a blank one
   or one that can be recycled.

   Because it writes filemarks to the complete length of the tape, the
   command can take from several hours to more than a day to complete.

OPTIONS

   -tape <tape special file>
       Specifies the UNIX device name of the tape device for which to
       determine filemark size and the capacity of the tape it currently
       contains. The format varies on different system types, but usually
       begins with /dev; an example is /dev/sd0a.

   -help
       Prints the online help for this command. All other valid options
       are ignored.

OUTPUT

   The command generates output both on the standard output stream and in
   the fms.log file that it creates in the current working directory. The
   output reports the capacity of the tape in the device and the device's
   filemark size.

   The first few lines of output include status information about the
   execution of the command, including such information as the number of
   blocks and the number of file marks written to the tape by the command.
   The last two lines of both screen and file output provide the following
   information:

   *   "Tape capacity is number bytes": specifies the size, in bytes, of
       the tape in the device.

   *   "File marks are number bytes": specifies the device's filemark size
       in bytes.

   The following message indicates that the fms command interpreter cannot
   access the tape device. The command halts.

      Can't open tape drive I<device>

   The following message indicates that the command interpreter cannot
   create the fms.log log file. Again, the command halts.

      Can't open log file

EXAMPLES

   The following command illustrates the output for the device called
   /dev/rmt1h:

      % fms /dev/rmt1h
      wrote block: 130408
      Finished data capacity test - rewinding
      wrote 1109 blocks, 1109 file marks
      Finished file mark test
      Tape capacity is 2136604672 bytes
      File marks are 1910205 bytes

   The following appears in the fms.log file:

      fms test started
      wrote 9230 blocks
      Finished file mark test
      Tape capacity is 151224320 bytes
      File marks are 2375680 bytes

PRIVILEGE REQUIRED

   The issuer must be able to insert and write to files in the currently
   working directory, if the fms.log file does not already exist. If it
   already exists, the issuer need only be able to write to it.

SEE ALSO

   fms.log(5), tapeconfig(5)

COPYRIGHT

   IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved.

   This documentation is covered by the IBM Public License Version 1.0.
   It was converted from HTML to POD by software written by Chas Williams
   and Russ Allbery, based on work by Alf Wachsmann and Elizabeth Cassell.

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