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


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

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


       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
       IBM AFS Administration Guide chapter on configuring the Backup System.

       Insert a tape in the drive before issuing this command.


       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 IBM AFS 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.


       -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.

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


       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

       ·   "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


       The following command illustrates the output for the device called

          % 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


       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.


       fms.log(5), tapeconfig(5)


       IBM Corporation 2000. <> 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.