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 beginning of the dump on file `/etc/ddate'. This file records a separate 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 dump

dump 0u

Next, periodic level 9 dumps should be made on an exponential progression 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.)

dump 9u

When the level 9 incremental approaches a full tape (about 78000 blocks at 1600 BPI blocked 20), a level 1 dump should be made.

dump 1u

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.