date and time created 88/07/21 17:35:50 by marc

[unix-history] / usr / src / local / ukc / dump / dump.8

.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)dump.8	6.3 (Berkeley) 5/23/86
.\"	@(#)dump.8	1.3 (UKC) %G%
.\"
.TH DUMP 8 "UKC altered %G%"
.UC 4
.SH NAME
dump \- incremental file system dump
.SH SYNOPSIS
.B /etc/dump
[ key [
.I argument
\&... ] filesystem ]
.SH DESCRIPTION
.I Dump
copies to magnetic tape all files
changed after a certain date
in the
.I filesystem.
The
.I key
specifies the date and other options about the dump.
.I Key
consists of characters from
the set
.B 0123456789fusdWnolmt.
.TP 5
.B  0\-9
This number is the `dump level'.
All files modified since the last date stored
in the file
.I /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
.B 0
causes the entire filesystem to be dumped.
.TP 5
.B f
Place the dump on the next 
.I argument 
file
instead of the tape.
If the name of the file is ``\-'',
.I dump 
writes to standard output.
.TP 5
.B u
If the dump completes successfully,
write the date of the beginning of the dump on
file
.I /etc/dumpdates.
This file records a separate date for
each filesystem and each dump level.
The format of
.I /etc/dumpdates
is readable by people, consisting of one
free format record per line:
filesystem name, increment level
and
.I ctime(3)
format dump date.  
.I /etc/dumpdates
may be edited to change any of the fields,
if necessary.
.TP 5
.B s
The size of the dump tape is specified in feet.
The number of feet is taken from the next
.I argument.
When the specified size is reached,
.I dump
will wait for reels to be changed.
The default tape size is 2300 feet.
.TP 5
.B d
The density of the tape, expressed in BPI,
is taken from the next
.I argument.
This is used in calculating the amount of tape
used per reel. The default is 1600.
.TP 5
.B W
.I Dump
tells the operator what file systems need to be dumped.
This information is gleaned from the files
.I /etc/dumpdates
and
.I /etc/fstab.
The
.B W
option causes
.I dump
to print out, for each file system in
.I /etc/dumpdates
the most recent dump date and level,
and highlights those file systems that should be dumped.
If the 
.B W
option is set, all other options are ignored, and
.I dump
exits immediately.
.TP 5
.B w
Is like W, but prints only those filesystems which need to be dumped.
.TP 5
.B n
Whenever
.I dump
requires operator attention,
notify by means similar to a
.IR wall (1)
all of the operators in the group \*(lqoperator\*(rq.
.PP
If no arguments are given,
the
.I key
is assumed to be
.B 9u
and a default file system is dumped
to the default tape.
.TP 5
.B o
This switch causes tapes to be rewound and the tape drive put offline after
each tape write has been done.
.TP 5
.B l
The next argument in the command list is a tape label.
The tape label is written into the dump file header at the beginning of each
tape which the dump uses.
Labels are currently limited to 15 characters.
The argument may contain a `%s', which is replaced by the volume number
in decimal of a multi-volume dump, unless the
.B m
argument is given (see below).
.PP
If the 
.B u
flag is set and the output device appears to be a tape drive,
each tape is logged in 
.IR /etc/dumpvolumes .
The data written here contains the tape label, the
name of the file system which has been dumped, the date, the device
which was dumped, the dump level, the reel of the dump and the inode
which the dump started from.
The log is written just prior to the tape being written, this means that
bad tapes will be logged.
When a tape is overwritten, its old entry in the log file can be removed
by the shell script /etc/cleanvolumes.
.TP 5
.B m
The m argument provides a way of mapping the volume numbers of a multi-volume dump
into a series of strings.
In the absence of an
.B l
argument, these strings become the tape label.
Otherwise the string is inserted in the tape label by the use of a `%s' marker
in the label format.
The argument to the
.B m
switch may be a single string or an auto-incrementing range.
These items may be grouped into a list by using commas to separate
each item.
An auto-incrementing range is two equal length strings separated by a minus
sign.
The first string is incremented starting at the rightmost character until
a match with the second string is acheived.
The increment treats the characters `0' to `9', `a' to `z', and `A' to `Z'
as separate ranges.
Examples to legal ranges are: 45-70, giving 45,46,47,48...69,70;
a00-b99, giving a00,a01,a02...b98,b99; and A0a-A9z, giving A0a,A0b,A0c...A9x,A9y,A9z.
.PP
.I Dump
will complain of the estimated number of tape which a dump will take is less
than the label range supplied by the user.
.TP 5
.B t
Tests that the tape being currently overwritten contains a header
bearing the correct label.
When a fresh tape is loaded, the first block is read and its label checked.
If the labels do not match, the write is refused on the tape.
This provides considerable protection and the ability to construct
tape dump cycles.
A program
.IR dumplabel (8)
may be used to label tapes prior to the use of
.IR dump .
.PP
.I Dump
requires operator intervention on these conditions:
end of tape,
end of dump,
tape write error,
tape open error or
disk read error (if there are more than a threshold of 32).
In addition to alerting all operators implied by the
.B n
key,
.I dump
interacts with the operator on 
.I dump's
control terminal at times when
.I dump
can no longer proceed,
or if something is grossly wrong.
All questions
.I dump
poses
.B must
be answered by typing \*(lqyes\*(rq or \*(lqno\*(rq,
appropriately.
.PP
Since making a dump involves a lot of time and effort for full dumps,
.I dump
checkpoints itself at the start of each tape volume.
If writing that volume fails for some reason,
.I 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.
.PP
.I 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
.I dump
is busy,
and will be for some time.
.PP
Now a short suggestion on how to
perform dumps.
Start with a full level 0 dump
.PP
	dump 0un
.PP
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:
.ce 1
3 2 5 4 7 6 9 8 9 9 ...
For the daily dumps, a set of 10 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 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 tapes that is saved forever.
.SH FILES
.nf
.ta \w'/etc/dumpvolumes\ \ 'u
/dev/rrp1g	default filesystem to dump from
/dev/rmt8	default tape unit to dump to
/etc/dumpdates	new format dump date record 
/etc/dumpvolumes	Listing of tape labels and the data which the tapes contain
/etc/fstab	dump table: file systems and frequency
/etc/group	to find group \fIoperator\fP
.fi
.DT
.br
.SH "SEE ALSO"
restore(8),
dumplabel(8),
dumpdev(8),
dump(5),
fstab(5)
.SH DIAGNOSTICS
Many, and verbose.
.PP
Dump exits with zero status on success.
Startup errors are indicated with an exit code of 1;
abnormal termination is indicated with an exit code of 3.
.SH BUGS
.PP
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.
.PP
.I Dump
with the
.B W
or
.B w
options does not report filesystems that have never been recorded
in /etc/dumpdates, even if listed in /etc/fstab.
.PP
It would be nice if
.I 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
.IR restore .