FMS(8)							       AFS Command Reference							    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:

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

       o   "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.

OpenAFS 							    2012-03-26								    FMS(8)