dump - incremental file system dump
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 0123456789fusd.
f Place the dump on the next argument file instead of the tape.
u If the dump completes successfully, write the date of the begin‐
ning of the dump on file `/etc/ddate'. This file records a sepa‐
rate date for each filesystem and each dump level.
0-9 This number is the `dump level'. All files modified since the
last date stored in the file `/etc/ddate' for the same filesystem
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.
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, the dump will wait for reels to be changed. The default
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
write. The default is 1600.
If no arguments are given, the key is assumed to be 9u and a default
file system is dumped to the default tape.
Now a short suggestion on how perform dumps. Start with a full level 0
Next, periodic level 9 dumps should be made on an exponential progres‐
sion of tapes. (Sometimes called Tower of Hanoi - 1 2 1 3 1 2 1 4 ...
tape 1 used every other time, tape 2 used every fourth, tape 3 used
every eighth, etc.)
When the level 9 incremental approaches a full tape (about 78000 blocks
at 1600 BPI blocked 20), a level 1 dump should be made.
After this, the exponential series should progress as uninterrupted.
These level 9 dumps are based on the level 1 dump which is based on the
level 0 full dump. This progression of levels of dump can be carried
as far as desired.
default filesystem and tape vary with installation.
/etc/ddate: record dump dates of filesystem/level.
restor(1), dump(5), dumpdir(1)
If the dump requires more than one tape, it will ask you to change
tapes. Reply with a new-line when this has been done.
Sizes are based on 1600 BPI blocked tape. The raw magtape device has
to be used to approach these densities. Read errors on the filesystem
are ignored. Write errors on the magtape are usually fatal.