NAME

dump − incremental file system dump

SYNOPSIS

dump [ key [ argument ... ] filesystem ]

DESCRIPTION

Dump copies to tape or disk 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 0123456789bfuJsdWn. 

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 or dump device [such as a floppy or hard disk] instead of the default tape. 

b Specifies the number of blocks on the dump device.  Used to specify the number of blocks floppy disks will hold, so that the dump will pause while disks are changed. 

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.  The format of /etc/ddate is readable by people, consisting of one free format record per line: filesystem name, increment level and ctime(3) format dump date.  /etc/ddate may be edited to change any of the fields, if necessary. 

s The size of a 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. 

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 disk or tape, end of dump, disk write error, disk or tape open error or read error. 

With tape, errors are not reported until they pass a threshold of 32.  With floppy disks, you can turn errors on or off.  If errors are turned on, all errors are reported.  If errors are turned off, errors are only reported if they are "hard" or fatal errors. 

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 disk or tape volume.  If writing that volume fails for some reason, dump will, with operator permission, restart itself from the checkpoint after the old disk or tape has been removed, and a new disk or tape has been mounted. 

Dump tells the operator what is going on at periodic intervals, including usually low estimates of the number of blocks to write, the number of disks or tapes it will take, the time to completion, and the time to the disk or 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

dump 0u

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 sets of disks or 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 sets of disks or 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 disks or tapes that is saved forever.

EXAMPLE

dump  0bf 2310 /dev/rfdc0 /dev/rmsc0a

would perform a level "0" dump to the floppy disk device rfdc0, which has 2310 blocks.  The filesystem to be dumped is /dev/rmsc0a.  Note that all the parameters in the key are grouped first in the command line, followed by the dump device (if other than tape), size etc.  The last argument should be the pathname of the file system being dumped. 

FILES

/dev/rmt8default tape unit to dump to
/etc/ddatedump date record

SEE ALSO

restor(8), dump(5), dumpdir(8)

DIAGNOSTICS

Many, and verbose. 

BUGS

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 restor. 

7th Edition  —  1/20/82