tapeconfig - Defines parameters for tape devices and backup data files
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
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>
- 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
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
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.
- 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
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.
- 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).
- 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.
Creating the file requires UNIX "w" (write) and "x"
(execute) permissions on the /var/lib/openafs/backup
the file requires UNIX "w" (write) permission on the file.
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,
, 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
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