NAME

dump − incremental file system dump

SYNTAX

dump [ key [ argument... ] filesystem ]

DESCRIPTION

The dump command copies to the dump media, usually magnetic tape, all files changed after a certain date in the filesystem.  The key specifies the date and other options about the dump.  The key argument consists of characters from the set 0123456789fusdmy. 

Before beginning the dump startup confirmation is requested.  This helps prevent accidental overwriting of file systems due to improper dump file specifications. 

KEYS

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. 

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. 

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. 

m Micro/pdp-11, dump to RX50 diskettes instead of tape.  The f option must also be specified when m is used.  For example:

dump 0umf /dev/rrx2 /dev/rrd0

k Dumps file to a TK50 instead of tape. 

y Suppress the start of dump confirmation query, allows for non-interactive use of dump. 

t Prevent rewrite on error.  Normally, when it encounters an error, dump prompts if the volume is to be rewritten.  With t specified, dump exits with status 1.  This is useful for letting a controlling process or script determine how to proceed on error. 

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, and so on.

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.

RESTRICTIONS

Sizes are based on 1600 BPI blocked tape.  The raw magtape device has to be used to approach these densities. 

DIAGNOSTICS

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. 

Unless the y option is specified dump asks for confirmation, as follows:

Last chance before writing on /dev/r??##
Continue <y or n> ?

A read error on the file system will result in an error message, but the dump will continue.

Unrecoverable write errors on the dump device cause the dump of the current volume to be aborted.  The dump program will ask if the current volume is to be rewritten.  Answer yes to continue the dump with the current volume or no to abort the entire dump. 

FILES

/dev/null  - default file system to be dumped
/dev/rht0  - default dump device
/etc/ddate - record dump dates of filesystem/level.

SEE ALSO

dump(5), dumpdir(8), restor(8)
ULTRIX-11 System Management Guide