DUMP(8) System Manager's Manual DUMP(8)
dump - incremental file system dump
/etc/dump [ key [ argument ... ] filesystem ]
Dump copies to magnetic tape all files changed after a certain date in
the filesystem. The key specifies the date and other options about the
dump. Key consists of characters from the set 0123456789fusdWn.
0-9 This number is the `dump level'. All files modified since the
last date stored in the file /etc/dumpdates for the same filesys-
tem at lesser levels will be dumped. If no date is determined by
the level, the beginning of time is assumed; thus the option 0
causes the entire filesystem to be dumped.
f Place the dump on the next argument file instead of the tape. If
the name of the file is ``-'', dump writes to standard output.
u If the dump completes successfully, write the date of the begin-
ning of the dump on file /etc/dumpdates. This file records a sep-
arate date for each filesystem and each dump level. The format of
/etc/dumpdates is readable by people, consisting of one free for-
mat record per line: filesystem name, increment level and ctime(3)
format dump date. /etc/dumpdates may be edited to change any of
the fields, if necessary.
s The size of the dump tape is specified in feet. The number of
feet is taken from the next argument. When the specified size is
reached, dump will wait for reels to be changed. The default tape
size is 2300 feet.
d 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
reel. The default is 1600.
W Dump tells the operator what file systems need to be dumped. This
information is gleaned from the files /etc/dumpdates and
/etc/fstab. The W option causes dump to print out, for each file
system in /etc/dumpdates the most recent dump date and level, and
highlights those file systems that should be dumped. If the W
option is set, all other options are ignored, and dump exits imme-
w Is like W, but prints only those filesystems which need to be
n Whenever dump requires operator attention, notify by means similar
to a wall(1) all of the operators in the group "operator".
If no arguments are given, the key is assumed to be 9u and a default
file system is dumped to the default tape.
Dump requires operator intervention on these conditions: end of tape,
end of dump, tape write error, tape open error or disk read error (if
there are more than a threshold of 32). In addition to alerting all
operators implied by the n key, dump interacts with the operator on
dump's control terminal at times when dump can no longer proceed, or if
something is grossly wrong. All questions dump poses must be answered
by typing "yes" or "no", appropriately.
Since making a dump involves a lot of time and effort for full dumps,
dump checkpoints itself at the start of each tape volume. If writing
that volume fails for some reason, dump will, with operator permission,
restart itself from the checkpoint after the old tape has been rewound
and removed, and a new tape has been mounted.
Dump tells the operator what is going on at periodic intervals, includ-
ing usually low estimates of the number of blocks to write, the number
of tapes it will take, the time to completion, and the time to the tape
change. The output is verbose, so that others know that the terminal
controlling dump is busy, and will be for some time.
Now a short suggestion on how to perform dumps. Start with a full
level 0 dump
Next, dumps of active file systems are taken on a daily basis, using a
modified Tower of Hanoi algorithm, with this sequence of dump levels:
3 2 5 4 7 6 9 8 9 9 ...
For the daily dumps, a set of 10 tapes per dumped file system is used
on a cyclical basis. Each week, a level 1 dump is taken, and the daily
Hanoi sequence repeats with 3. For weekly dumps, a set of 5 tapes per
dumped file system is used, also on a cyclical basis. Each month, a
level 0 dump is taken on a set of fresh tapes that is saved forever.
/dev/rrp1g default filesystem to dump from
/dev/rmt8 default tape unit to dump to
/etc/ddate old format dump date record (obsolete after -J option)
/etc/dumpdates new format dump date record
/etc/fstab dump table: file systems and frequency
/etc/group to find group operator
restore(8), dump(5), fstab(5)
Many, and verbose.
Sizes are based on 1600 BPI blocked tape; the raw magtape device has to
be used to approach these densities. Fewer than 32 read errors on the
filesystem are ignored. Each reel requires a new process, so parent
processes for reels already written just hang around until the entire
tape is written.
It would be nice if dump knew about the dump sequence, kept track of
the tapes scribbled on, told the operator which tape to mount when, and
provided more assistance for the operator running restore.
4th Berkeley Distribution 4 February 1983 DUMP(8)