DUMP(1M) Silicon Graphics DUMP(1M)
NAME
dump, rdump - incremental file system dump
SYNOPSIS
/usr/etc/dump [ key [ argument ... ] ] filesystem
/usr/etc/rdump [ key [ argument ... ] ] filesystem
DESCRIPTION
dump backs up all files in filesystem, or files changed after a certain
date to magnetic tape or files. The key specifies the date and other
options about the dump. Key consists of characters from the set
0123456789fuscdbWwn. Any arguments supplied for specific options are
given as subsequent words on the command line, in the same order as that
of the options listed.
If no key is given, the key is assumed to be 9u and the filesystem
specified is dumped to the default tape device /dev/tape.
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. For instance, if you did a
"level 2" dump on Monday, followed by a "level 4" dump on Tuesday, a
subsequent "level 3" dump on Wednesday would contain all files
modified or added to the filesystem since the "level 2" (Monday)
backup. A "level 0" dump copies the entire filesystem to the
dump volume.
f Place the dump on the next argument file instead of the default tape
device /dev/tape. If the name of the file is ``-'', dump writes to
standard output. If the name of the file is of the format
machine:device the filesystem is dumped across the network to the
remote machine. Since dump is normally run by root, the name of the
local machine must appear in the .rhosts file of the remote machine.
If the file name argument is of the form user@machine:device, dump
will attempt to execute as the specified user on the remote machine.
The specified user must have a .rhosts file on the remote machine
that allows root from the local machine. dump creates a remote
server, /etc/rmt, on the client machine to access the tape device.
u If the dump completes successfully, write the date of the beginning
of the dump 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, consisting of one free format
record per line: filesystem name, increment level and ctime(3C)
format dump date. /etc/dumpdates may be edited to change any of the
fields, if necessary.
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,
dump will prompt the operator and wait for the reel/volume to be
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changed. The default tape size for the standard half inch reels is
2400 feet. The default for cartridge tapes is an effective tape
length of 5400 feet, and this assumes a 9-track QIC-24 tape whose
physical tape length is 600 feet. See note on cartridge tapes
parameters below.
d The density of the tape, expressed in BPI (bytes per inch), is taken
from the next argument. This is used in calculating the amount of
tape used per reel. The default is 1600 BPI, except for the
cartridge tape which has a default density of 1000 BPI. Unless a
higher density is specified explicitly, dump uses its default
density - even if the tape drive is capable of higher-density
operation (for instance 6250 BPI). If the density specified does
not correspond to the density of the tape device being used, dump
will not be able to handle end-of-tape properly.
b The blocking factor (number of 1 Kbyte blocks written out together)
is taken from the next argument. The default is 10. The default
blocking factor for tapes of density 6250 BPI and greater is 32. To
maximize tape utilization, use a blocking factor which is a multiple
of 8.
c Indicates that the tape is a cartridge tape instead of the standard
default half-inch reel. This should always be specified when using
cartridge tapes. The values for blocking factor, size and density
are taken to be 10 (1 KByte blocks), 5400 feet and 1000 BPI
respectively unless overridden with the 'b', 's' or 'd' option.
Cartridge tapes with multiple tracks have a greater effective length
which can be specified with the 's' option.
W dump tells the operator what file systems 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 file system in
/etc/dumpdates the most recent dump date and level, and highlights
those file systems that should be dumped. The mnt_freq field in the
/etc/fstab entry of the file system must be non-zero for dump to
determine whether the file system should be dumped or not. If the W
option is set, no other option must be given, and dump exits
immediately.
w Is like W, but prints only those filesystems which need to be
dumped.
n Whenever dump requires operator attention, notify by means similar
to a wall(1) all of the operators in the group "operator".
dump reads the character device associated with the filesystem and dumps
the contents onto the specified tape device. It searches /etc/fstab to
find the associated character device.
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NOTES
rdump is a link to dump.
Operator Intervention
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 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 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 reports periodically including usually the percentage of the dump
completed, 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 estimated time is given as hours:minutes and is based on the
the time taken to dump the blocks already on tape. It is normal for this
estimate to show variance and the estimate improves over time. The
output is verbose, so that others know that the terminal controlling dump
is busy, and will be for some time.
Suggested Dump Schedule
It is vital to perform full, "level 0, dumps at regular intervals. When
performing a full dump, bring the machine down to single-user mode using
shutdown(1M). While preparing for a full dump, it is a good idea to
clean the tape drive and heads.
Incremental dumps allow for convenient backup and recovery on a more
frequent basis of active files, with a minimum of media and time.
However there are some tradeoffs. First, the interval between backups
should be kept to a minimum (once a day at least). To guard against data
loss as a result of a media failure (a rare, but possible occurrence), it
is a good idea to capture active files on (at least) two sets of dump
volumes. Another consideration is the desire to keep unnecessary
duplication of files to a minimum to save both operator time and media
storage. A third consideration is the ease with which a particular
backed-up version of a file can be located and restored. The following
four-week schedule offers a reasonable tradeoff between these goals.
Sun Mon Tue Wed Thu Fri
Week 1: Full 5 5 5 5 3
Week 2: 5 5 5 5 3
Week 3: 5 5 5 5 3
Week 4: 5 5 5 5 3
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DUMP(1M) Silicon Graphics DUMP(1M)
Although the Tuesday - Friday incrementals contain "extra copies" of
files from Monday, this scheme assures that any file modified during the
week can be recovered from the previous day's incremental dump.
Dump Parameters
The following table gives a list of available tape formats, size and
densities. It is important that the correct parameters be given to dump,
if they are different from the defaults.
Parameters for cartridge tapes
Cartrige Interface QIC-24 QIC-120 QIC-150
Number of Tracks 9 15 18
Physical Tape Length (feet) 600 600 600
Effective Tape Length (feet) 5400 9000 10800
Cartridge tapes with multiple tracks have an greater effective length.
The tape lengths give above assume a physical tape length of 600 feet. In
general the effective tape length can be calculated by multiplying the
physical tape length by the number of tracks. Since some tape is usually
lost due to tape errors, and because dump does not handle end-of-tape
gracefully, it pays to be conservative in estimating the effective tape
length.
Parameters for half-inch tapes
Thickness
Reel Sizes (inches) 6.0 7.0 8.5 10.5
Tape Length (feet) 200 600 1200 2400 1.9 mm
3600 1.3 mm
The density for these tapes can be any one of the following: 800, 1600,
3200 or 6250 BPI.
Parameters for 8mm tapes
Tape Type length capacity
(meters) (Mbytes)
P5 (European) 112 2200
P6 (American) 112 2000
There is a bug in
dump
which causes it to miscalculate the number of tapes required when
it is given a large value for the density and a small value for
tape length. To work around this,
use a density of 54000 and length of 6000 feet while using 8mm tapes,
rather than the actual density and length.
EXAMPLES
/dev/usr /usr efs rw,raw=/dev/rdsk/dks0d1s6 0 0
Here are a few examples on how to dump the /usr filesystem with the above
/etc/fstab entry.
dump 0fuc guest@kestrel:/dev/tape /usr
will do a level '0' dump of /usr on to a remote cartridge tape device
/dev/tape on host kestrel using the guest account. dump also updates the
file /etc/dumpdates.
dump 2uc /usr
does a level '2' dump of /usr to the local cartridge tape device
/dev/tape and also updates the file /etc/dumpdates.
dump 0sdb 10800 1000 32 /usr
does a level '0' dump of /usr to the local tape device /dev/tape using a
blocking factor of 32. The tape is assumeed to have a length of 10800
feet with a density of 1000 BPI. The ordering of the arguments is
dependent on the ordering of the key.
dump 1sfc 10800 /dev/mt/tps0d7 /usr
dump 1sfc 10800 /dev/mt/tps0d7 /dev/rdsk/dks0d1s6
both do a level '1' dump of /usr to the local cartridge tape device
/dev/mt/tps0d7 using a tape length of 10800 feet.
dump /usr
does a level '9' dump of /usr to the local tape device /dev/tape and
updates the file /etc/dumpdates.
dump 9ucdsf 54000 6000 /dev/mt/tps0d6nrnsv /os
does a level '9' dump of /os to the local tape device /dev/mt/tps0d6nrnsv
using a tape density of 54000 BPI and tape length of 6000 feet where the
tape device being used is an 8mm tape drive.
dump W
prints out, for each file system in /etc/dumpdates the most recent dump
date and level, and highlights those file systems that should be dumped.