perform XENIX incremental filesystem backup
[ key [ arguments ] filesystem ]
copies all files changed after a certain date in the filesystem.
xbackup is used for XENIX filesystems; use
for UNIX filesystems.
(xdump is a link to xbackup, retained for
The key specifies the date and other options about the
xbackup, where a key
consists of characters from the set: 0123456789kfusd.
The meanings of these characters are described below:
If no arguments are given, the key is assumed to be
9u and a default filesystem is backed up to the default device.
Places the backup on the file specified by the next
argument instead of the default device.
If the xbackup completes successfully,
writes the date of the beginning of the xbackup to the file
This file records a separate date for
each filesystem and each xbackup level.
This number is the xbackup level.
Backs up all files modified since the last date stored in the file
/etc/ddate for the same filesystem at lesser levels.
If no date is determined by the level, the beginning of time is assumed;
thus the option 0 causes the entire filesystem to be backed up.
For xbackups to magnetic tape, the size of the tape is specified in feet.
The number of feet is taken from the next argument.
When the specified size is reached, xbackup
will wait for reels to be changed.
The default size is 2,300 feet.
For xbackups to magnetic tape, 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.
The size (in Kilobytes) of the volume being written is taken from the next
If the k argument is specified, any s
and d arguments are ignored.
The default is to use s and d.
The first xbackup should be a full level-0 xbackup:
Next, periodic level 9 xbackups should be made on an
exponential progression of tapes or floppies:
This progression is shown as follows:
1 2 1 3 1 2 1 4 ...
where xbackup 1 is used every other time,
xbackup 2 every fourth, xbackup 3 every eighth, etc.)
When the level-9 incremental xbackup becomes
unmanageable because a tape is full or too many floppies are required,
a level-1 xbackup should be made:
After this, the exponential series should progress as if uninterrupted.
These level-9 xbackups are based on the level-1 xbackup, which
is based on the level-0 full xbackup.
This progression of levels of xbackups can be carried
as far as desired.
The default filesystem and the xbackup device depend on the settings
of the variables DISK and TAPE respectively,
in the file /etc/default/backup.
If the xbackup 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.
If you have a XENIX filesystem, or have been administering one,
it is important to realize that you cannot use backups
created by the xbackup
utility. These backups do not allow downsizing when you restore.
This is true even if the backed-up filesystem is not full.
For example, if you back up a 20MB filesystem that
is only 50 percent full, you still won't be able to restore the
backup volumes onto a 15MB filesystem. The reinstallation
chapter explains that you must use
utilities (such as the Backup Manager) to back up your system.
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 Kilobytes.
Write errors to the backup device are usually fatal.
Read errors on the filesystem are ignored.
If the default archive medium specified in /etc/default/xbackup
or /etc/default/restor is block structured, (that is, floppy disk)
then the volume size in Kilobytes must be specified on the command line.
Neither utility works correctly without this information.
For example, using the default device (below) with the
xbackup command, enter the following:
xbackup k 360
The default device entry for /etc/default/xbackup (tape=/dev/xxx)
and /etc/default/restor (archive=/dev/xxx) is /dev/rfd02.
It is not possible to successfully restore
an entire active root filesystem.
When backing up to floppy disks, be sure to have enough
formatted floppies ready before starting an xbackup.
You must also be sure to close the floppy door when inserting floppy disks.
If you fail to do so in a multi-floppy xbackup,
the entire xbackup will fail and you will have to begin again.
You should never xbackup more than one filesystem to the
tape devices /dev/nrct0 and /dev/nrct2.
This is because, although xbackup 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.
records xbackup dates of filesystem/level
default xbackup information
``Understanding incremental backups'' in the System Administration Guide
xbackup is not part of any currently supported standard; it is
an extension of AT&T System V provided by
The Santa Cruz Operation, Inc.
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003