NAME

dump − incremental filesystem dump

SYNOPSIS

/etc/dump [ key [ arguments ] filesystem ]

DESCRIPTION

Dump copies to magnetic tape all files in the filesystem which were changed after a certain date. 

KEYS

The key specifies the date and other options about the dump.  It consists of characters from the following set. 

0−9 This number is the “dump level.”  All files modified since the last date stored in the file /etc/dumpdates, 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. 

d density
The density of the tape, expressed in BPI, is taken from the next argument, density.  This is used in calculating the amount of tape used per reel. The default is 1600. 

f Places the dump on the next argument file rather than on the tape.  If the name of the file is  − , dump writes to standard output. 

n Whenever dump requires operator attention, the system will notify by means similar to a wall(1), all of the operators in the group “operator”. 

s size The size of the dump tape is specified in feet.  The number of feet is taken from the next argument size.  When the specified size is reached, dump waits for reels to be changed.  The default tape size is 2300 feet. 

u If the dump completes successfully, the date of the beginning of the dump is written on file /etc/dumpdates.  This file records a separate date for each filesystem and each dump level.  The format of /etc/dumpdates is readable by people, and consists of one free format record per line: filesystem name, increment level and ctime(3) format dump date.  The file /etc/dumpdates may be edited to change any of the fields, if necessary. 

w Similar to W, but prints only those filesystems which need to be dumped. 

W Dump tells the operator what filesystems 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 filesystem in /etc/dumpdates, the most recent dump date and level, and it highlights those filesystems that should be dumped.  If the W option is set, all other options are ignored and dump exits immediately. 

If no arguments are given, the key is assumed to be 9u and a default filesystem is dumped to the default tape. 

Dump requires operator intervention on the following conditions: end of tape, end of dump, tape write error, tape open error or disk read error (if there are more of these 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 posed by dump must be answered by typing yes or no. 

Since making a full dump involves a lot of time and effort, 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, including 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. 

To perform dumps, it is suggested that the user start with a full level 0 dump

dump 0un

Next, dumps of active filesystems should be taken on a daily basis, using a modified Tower of Hanoi algorithm, with the following sequence of dump levels:

3 2 5 4 7 6 9 8 9 9 ... 

For the daily dumps, a set of ten tapes per dumped filesystem should be used on a cyclical basis.  Each week, a level 1 dump should be taken, and the daily Hanoi sequence repeated with 3.  For weekly dumps, a set of five tapes per dumped filesystem should be used, also on a cyclical basis.  Each month, a level 0 dump should be taken on a set of fresh tapes that is saved forever. 

FILES

/etc/ddateold format dump date record
/etc/dumpdatesnew format dump date record
/etc/fstabdump table: filesystems and frequency
/etc/groupto find group “operator”

SEE ALSO

restore(8), dump(5), fstab(5)

DIAGNOSTICS

Many verbose messages. 

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 an improvement 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  —  1 August 1985