Provided by: openafs-client_1.8.13.2-1ubuntu1_amd64 
NAME
tapeconfig - Defines parameters for tape devices and backup data files
DESCRIPTION
The tapeconfig file defines basic configuration parameters for all of the tape devices or backup data
files available for backup operations on a Tape Coordinator machine. The file is in ASCII format and must
reside in the local /var/lib/openafs/backup directory. The instruction for each tape device or backup
data file appears on its own line and each has the following format:
[<capacity> <filemark_size>] <device_name> <port_offset>
where
<capacity>
Specifies the capacity of the tapes used with a tape device, or the amount of data to write into a
backup data file. The Tape Coordinator refers to this value in two circumstances:
• When the capacity field of a tape or backup data file's label is empty (because the tape has
never been labeled). The Tape Coordinator records this value on the label and uses it when
determining how much data it can write to the tape or file during a backup dump or backup savedb
operation. If there is already a capacity value on the label, the Tape Coordinator uses it
instead.
• When the -size argument is omitted the first time the backup labeltape command is used on a given
tape or file. The Tape Coordinator copies this value into the label's capacity field.
The Tape Coordinator uses this capacity value or the one on the Backup System tape label to track how
much space remains as it writes data to a tape or backup data file. The appropriate value to record
for a tape depends on the size of the tapes usually used in the device and whether it has a
compression mode; for suggested values, see the OpenAFS Administration Guide chapter on configuring
the Backup System. If using a value obtained from the fms command, reduce it by 10% to 15% before
recording it in the file.
For a backup data file, it is best to provide a value that helps the Tape Coordinator avoid reaching
the end-of-file (EOF) unexpectedly. Make it at least somewhat smaller than the amount of space
available on the partition housing the file when the dump operation begins, and never larger than the
maximum file size allowed by the operating system.
Specify a (positive) integer or decimal value followed by a letter than indicates units, with no
intervening space. In a decimal number, the number of digits after the decimal point must not
translate to fractions of bytes. The maximum acceptable value is 2048 GB (2 TB). The acceptable units
letters are as follows; if the letter is omitted, the default is kilobytes.
• "k" or "K" for kilobytes (KB).
• "m" or "M" for megabytes (MB).
• "g" or "G" for gigabytes (GB).
• "t" or "T" for terabytes (TB).
If this field is omitted, the Tape Coordinator uses the maximum acceptable value (2048 GB or 2 TB).
Either leave both this field and the <filemark_size> field empty, or provide a value in both of them.
<filemark_size>
Specifies the size of a tape device's filemarks (also called end-of-file or EOF marks), which is set
by the device's manufacturer. In a dump to tape, the Tape Coordinator inserts filemarks at the
boundary between the data from each volume, so the filemark size affects how much space is available
for actual data.
The appropriate value to record for a tape depends on the size of the tapes usually used in the
device and whether it has a compression mode; for suggested values, see the OpenAFS Administration
Guide chapter on configuring the Backup System. If using a value obtained from the fms command,
increase it by 10% to 15% before recording it in the file.
For backup data files, record a value of 0 (zero). The Tape Coordinator actually ignores this field
for backup data files, because it does not use filemarks when writing to a file.
Use the same notation as for the <capacity> field, but note that the default units is bytes rather
than kilobytes. The maximum acceptable value is 2048 GB.
If this field is empty, the Tape Coordinator uses the value 0 (zero). Either leave both this field
and the <capacity> field empty, or provide a value in both of them.
<device_name>
Specifies the complete pathname of the tape device or backup data file. The format of tape device
names depends on the operating system, but on UNIX systems device names generally begin with the
string /dev/. For a backup data file, this field defines the complete pathname; for a discussion of
suggested naming conventions see the description of the "FILE" instruction in butc(5).
<port_offset>
Specifies the port offset number associated with this combination of Tape Coordinator and tape device
or backup data file.
Acceptable values are the integers 0 through 58510 (the Backup System can track a maximum of 58,511
port offset numbers). Each value must be unique among the cell's Tape Coordinators, but any number
of them can be associated with a single machine. Port offset numbers need not be assigned
sequentially, and can appear in any order in the tapeconfig file. Assign port offset 0 to the Tape
Coordinator for the tape device or backup data file used most often for backup operations; doing so
will allow the operator to omit the -portoffset argument from the largest possible number of backup
commands.
PRIVILEGE REQUIRED
Creating the file requires UNIX "w" (write) and "x" (execute) permissions on the /var/lib/openafs/backup
directory. Editing the file requires UNIX "w" (write) permission on the file.
EXAMPLES
The following example tapeconfig file configures three tape devices and a backup data file. The first
device has device name /dev/rmt/0h, and is assigned port offset 0 because it will be the most frequently
used device for all backup operations in the cell. Its default tape capacity is 2 GB and filemark size is
1 MB. The /dev/rmt/3h drive has half the capacity but a much smaller filemark size; its port offset is 3.
The third device listed, /dev/rmt/4h, has the same capacity and filemark size as the first device and is
assigned port offset 2. Port offset 4 is assigned to the backup data file /dev/FILE, which is actually a
symbolic link to the actual file located elsewhere on the local disk. The Tape Coordinator writes up to
1.5 GB into the file; as recommended, the filemark size is set to zero.
2G 1M /dev/rmt/0h 0
1g 4k /dev/rmt/3h 3
2G 1m /dev/rmt/4h 2
1.5G 0 /dev/FILE 4
SEE ALSO
backup_addhost(8), backup_dump(8), backup_labeltape(8), backup_savedb(8), butc(8), fms(8)
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 2025-03-21 TAPECONFIG(5)