backup(8) CLIX backup(8)
NAME
backup, backupffs - Backs up a file system incrementally
SYNOPSIS
/bin/backup [key[argument ... ] file-system]
FLAGS
0-9 Specifies the backup level. All files at lesser levels in
file-system modified since the date stored for this level in
the /etc/dumpdates file will be backed up. If no date is
determined by the level, the earliest possible date is
assumed; thus, the key 0 causes the entire file-system to be
backed up.
f special Places the backup on special tape (whether local or remote)
instead of on the default tape. The rtc command can be used
with backup to back up to a remote tape device.
u Writes the date of the beginning of the backup on the
/etc/dumpdates file if the backup completes successfully.
This file records a separate date for each file-system and
each backup level. The format of /etc/dumpdates is readable
text, consisting of one free format record per line: file-
system name, increment level and backup date. The
/etc/dumpdates file may be edited to change any of the fields
if necessary.
s size Specifies the size of the backup tape in feet. The number of
feet is indicated by the size. When the specified size (size)
is reached, backup will wait for reels to be changed. The
default tape size is 2300 feet. A gap length of 0.8 inches is
assumed for each write to the tape.
d size Specifies the density of the tape, expressed in bytes per inch
(BPI). This value is taken from size. The size parameter is
used in calculating the amount of tape used per reel. The
default density is 1600 BPI.
W Lists what file systems need to be backed up. This
information is gathered from the files /etc/dumpdates and
/etc/fstab. For each file system in /etc/dumpdates, backup
displays the most recent backup date and level, and highlights
the file systems that should be backed up. If the W key is
set, all other keys are ignored and backup exits immediately.
w Resembles W, but displays only the file systems that need to
be backed up.
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backup(8) CLIX backup(8)
n Notifies all of the users in the group ``operator'' when
backup requires operator attention.
b blocks Specifies the number of 1K byte blocks written to the tape at
a time. This value is indicated by blocks. This number will
affect how much tape is used for gaps between writes. The
block parameter cannot exceed 10 when using /dev/rmt/rtc* as
the tape device (see rtc and the f key above).
c Specifies that a cartridge tape is being used. The default
density is 8700 BPI. The default length is 600 feet. A gap
length of 0 is assumed.
X Specifies that a 2.2 gigabyte (GB) exabyte cartridge tape is
being used. The default density is 43200 BPI. The default
length is 360 feet. A gap length of 0 is assumed.
Y Specifies that a 5 GB exabyte cartridge tape is being used.
The default density is 86400 BPI. The default length is 360
feet. A gap length of 0 is assumed.
DESCRIPTION
The backup command copies files to magnetic tape. If the file system is a
Fast File System, the backup will invoke backupffs automatically.
The backup command copies to magnetic tape all files changed after a
certain date in the file-system. The key is a string of alphanumeric
characters that specifies the date and other options about the backup.
The argument specifies options for certain keys.
The key may be any of the characters from the set 0123456789fusdWnbcX,
defined in the FLAGS section.
If no arguments are given, the key is assumed to be 9u and a default file
system (/dev/dsk/s0u0p7.3) is backed up to the default tape.
The backup command requires operator intervention on these conditions:
end-of-tape, end of backup, tape write error, tape open error, or disk
read error (if more than 32 disk errors occur). In addition to alerting
all operators implied by the n key, backup interacts with the operator on
backup's control terminal when the routine can no longer proceed. All
questions backup poses must be answered by typing ``yes'' or ``no''
appropriately.
Since a full backup requires much time and effort, backup checkpoints
itself at the start of each tape volume. If writing the volume fails,
backup will, with operator permission, restart from the checkpoint after
the old tape has been rewound and removed and a new tape has been mounted.
The backup command initially informs the operator of the number of blocks
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backup(8) CLIX backup(8)
to write, the number of tapes the write will take, and the time until
completion. In addition, backup periodically informs the operator of the
time until the tape change. The output is verbose so that others know
that the terminal controlling backup is busy, and will be for some time.
The recommended method of performing backups is to first start with a full
level 0 backup. Next, active file systems are backed up daily, using a
modified Tower of Hanoi algorithm with this sequence of backup levels:
3 2 5 4 7 6 9 8 9 9 ...
For the daily backups, a set of 10 tapes per backed up file system is used
on a cyclical basis. Each week, a level 1 backup is performed and the
daily Hanoi sequence repeats with 3. For weekly backups, a set of five
tapes per backed-up file system is used. The set is also used on a
cyclical basis. Each month, a level 0 backup is performed on a set of
fresh tapes that is saved permanently.
EXAMPLES
1. To perform a full backup, enter the following:
backup 0un
This backs up the entire file system to tape and writes the date of
the backup to the /etc/dumpdates file if the backup completes
successfully.
2. The following example does a backup using another machine's (bigsys)
tape drive. The tape drive on bigsys is a cartridge tape. The backup
is an incremental (level 9) backup.
rtc -a -s bigsys -r /dev/rmt/mt5 -n /dev/rmt/mt5n /dev/rmt/rt0.ctl
backup 9uncf /dev/rmt/rt0.
FILES
/dev/dsk/s0u0p7.3 Default file system to backup.
/dev/rmt/0m Default tape unit to which to send the backup.
/etc/dumpdates Backup date record.
/etc/fstab Backup table of file systems.
/etc/group To find operator group.
NOTES
This command requires superuser privileges.
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backup(8) CLIX backup(8)
CAUTIONS
Fewer than 32 read errors on the file system are ignored. Each reel
requires a new process, so parent processes for reels already written wait
until the entire tape is written.
Issuing the backup command with W or w does not report file systems that
are not recorded in /etc/dumpdates even if they are listed in /etc/fstab.
EXIT VALUES
The backup command exits with a value of 0 if successful. If
unsuccessful, one of the following values is returned:
1 Startup errors occurred.
3 Abnormal termination occurred.
RELATED INFORMATION
Commands: restore(1), rtc(1)
Files: backup(0), fstab(4)
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