dump(1m)
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dump
incremental file system dump
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SYNTAX
/etc/dump [ key [ argument ... ] special ]
DESCRIPTION
Dump copies to magnetic tape all files changed after a certain
date in a particular file system. Special is the pathname of a
special file referring to a device containing a file system. Key
specifies the date and other options about the dump. The key
consists of characters from the set 0123456789bcdfgJnsuWwz:
0-9 Indicate the dump level. All files modified since the last
date stored in the file /etc/dumpdates for the same file
system at lesser levels will be dumped. If no date is
determined by the level, the beginning of Jan. 1, 1970, GMT,
is assumed; thus the option 0 dumps the entire file system.
b Specify blocking factor, the number of 1024-byte blocks per
tape record. Default is 10; maximum is 32. Ideally, this
number will match the optimal blocking factor for the device
in use (e.g., it should be 7 or 16 for mtj and 8 for mtc).
g Specify a memory buffer size expressed as 1K blocks.
Default is set to the value of the -b option (or 10, if -b
is not used). The maximum is 2048. The buffer must be at
least the size and a multiple of the -b value and may also
be limited by memory available. Note that increasing this
buffer will allow you to stream devices. We suggest using
512 to stream mtj devices.
c The tape used is a cartridge tape. Dump(1M) considers this
factor when it determines how much it can write on one tape.
See also the s option.
d Take the density of the tape, expressed in bits per
inch(bpi), from the next argument. This is used in
calculating the amount of tape used per reel. The default
is 1600 bpi.
f Place the dump on the next argument file instead of the
tape. If you have DG TCP/IP (DG/UX), you can use this
option to dump to a remote device. For example, dump 0f
sys:/dev/rmt/0 /root lets you dump the root filesystem to
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the tape device "0" on system "sys."
J Convert the old, obsolete format to the new format. All
other options are ignored, and dump terminates immediately.
Invoke this option only when the old /etc/ddate files are
updated to the new /etc/dumpdates format.
n Notify an operator (as in wall(1M)) whenever a response is
required at the operator's console. /etc/group must contain
an entry for "operator."
s Specify the size of the dump tape in feet. The number of
feet is taken from the next argument. When the specified
size is reached, dump waits for reels to be changed. The
default tape size is 2300 feet. Type of tape (reel or
cartridge) is also a factor in dump's calculation of tape
length; see the c option.
u Write the date of the beginning of the dump on file
/etc/dumpdates, if the dump completes successfully. This
file records a separate date for each file system and each
dump level. You can read the format of /etc/dumpdates,
which consists of one free format record per line: file
system name, increment level, and ctime(3)-format dump date.
You can edit /etc/dumpdates to change any of the fields.
Note that /etc/dumpdates is formatted differently from
previous versions of dump in /etc/ddate, although it
contains identical information.
W Tell the operator what file systems need to be dumped. This
information is gleaned from the files /etc/dumpdates and
/etc/fstab. Dump prints out the most recent dump date and
level for each file system in /etc/dumpdates, and highlights
those file systems that should be dumped. All other options
are ignored, and dump exits immediately.
w Do as W does, but print only those file systems that need to
be dumped.
z Print the inode numbers of dumped files on the standard
output.
If no arguments are given, key is assumed to be 9u and a default
file system is dumped to the default tape.
Dump and restore support symbolic links.
Dump requires operator intervention on end of tape, end of dump,
tape write error, tape open error, or disk read error (if there
are more than 32 errors). In addition to alerting all operators
(with the n key), dump interacts with the operator on dump's
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control terminal when dump can no longer proceed, or if something
is grossly wrong. All questions dump poses 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.
At periodic intervals, dump tells the operator what is going on,
usually including 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, start with a full level 0 dump:
dump 0un
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 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, which is saved indefinitely,
is taken on a set of fresh tapes.
FILES
/etc/dumpdates New format dump date record
/etc/fstab Dump table: file systems and frequency
/etc/group To find group operator
SEE ALSO
restore(1m), fstab(4).
DIAGNOSTICS
Many, and verbose.
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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 file system are ignored. Since each reel requires
a new process, parent processes for reels already written
continue until the entire tape is written.
Dump should know about the dump sequence, keep track of the tapes
used, tell the operator which tape to mount and when, and provide
more help to the operator running restore.
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