BACKUP(ADM) XENIX System V BACKUP(ADM)
Name
backup, dump - Performs incremental file system backup.
Syntax
backup [ key [ arguments ] filesystem ]
Description
backup copies all files changed after a certain date in the
filesystem. dump is a link to backup; they refer to the
same utility. The key specifies the date and other options
about the backup, where a key consists of characters from
the set 0123456789kfusd. The meanings of these characters
are described below:
f Places the backup on file specified by the next
argument instead of the default device.
u If the backup completes successfully, writes the date
of the beginning of the backup to the file /etc/ddate.
This file records a separate date for each file system
and each backup level.
0-9 This number is the ``backup level''. Backs up all
files modified since the last date stored in the file
/etc/ddate for the same file system at lesser levels.
If no date is determined by the level, the beginning of
time is assumed; thus the option 0 causes the entire
file system to be backed up.
s This is the size of the tape in feet. The number of
feet is taken from the next argument. When the
specified size is reached, backup will wait for reels
to be changed. The default size is 2,300 feet.
d This is the density of the tape, expressed in BPI, is
taken from the next argument. This is used in
calculating the amount of tape used per write. The
default is 1600.
k The size (in K-bytes) of the volume being written is
taken from the next argument. If the k argument is
specified, any s and d arguments are ignored. The
default is to use s and d.
If no arguments are given, the key is assumed to be 9u and a
default file system is backed up to the default device.
The first backup should be a full level-0 backup:
backup 0u
Next, periodic level 9 backups should be made on an
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BACKUP(ADM) XENIX System V BACKUP(ADM)
exponential progression of tapes or floppies:
backup 9u
This progression is shown as follows:
1 2 1 3 1 2 1 4 ...
where backup 1 is used every other time, backup 2 every
fourth, backup 3 every eighth, etc.) When the level-9
incremental backup becomes unmanageable because a tape is
full or too many floppies are required, a level-1 backup
should be made:
backup 1u
After this, the exponential series should progress as if
uninterrupted. These level-9 backups are based on the
level-1 backup, which is based on the level-0 full backup.
This progression of levels of backups can be carried as far
as desired.
The default file system and the backup device depend on the
settings of the variables DISK and TAPE, respectively, in
the file /etc/default/backup.
Files
/etc/ddate Records backup dates of file
system/level
/etc/default/backup Default backup information
See Also
XENIX System Administrator's Guide
cpio(C), default(F), dumpdir(ADM), restore(ADM), sddate(C),
backup(F)
Diagnostics
If the backup requires more than one volume (where a volume
is likely to be a floppy disk or tape), you will be asked to
change volumes. Press RETURN after changing volumes.
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BACKUP(ADM) XENIX System V BACKUP(ADM)
Notes
Sizes are based on 1600 BPI for blocked tape. Although the
s and d options are used by default, they are not commonly
used; the k option is more popular because it specifies size
in K-bytes. Write errors to the backup device are usually
fatal. Read errors on the file system are ignored.
If the default archive medium specified in
/etc/default/backup or /etc/default/restor is block
structured, (example: floppy disk) then the volume size in
Kbytes must be specified on the command line. Neither
utility works correctly without this information. For
example, using the default device (below) with the backup
command, enter the following:
backup k 360
The default device entry for /etc/default/backup
(tape=/dev/xxx) and /etc/default/restor (archive=/dev/xxx)
is /dev/rfd02.
It is not possible to successfully restore an entire active
root file system.
Warning
When backing up to floppy disks, be sure to have enough
formatted floppies ready before starting a backup. You must
also be sure to close the floppy door when inserting floppy
disks. If you fail to do so in a multi-floppy backup, the
entire backup will fail and you will have to begin again.
You should never backup more than one filesystem to the tape
devices /dev/nrct0 and /dev/nrct2. This is because,
although backup can write more than one filesystem to
/dev/nrct0 or /dev/nrct2, restore may not be able to restore
more than one filesystem from these devices.
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