DUMP(8) System Manager's Manual DUMP(8)
dump, rdump - incremental file system dump
/usr/etc/dump [ options [ arguments ] ] filesystem
/usr/etc/dump [ options [ arguments ] ] filename ...
/usr/etc/rdump [ options [ arguments ] ] filesystem
/usr/etc/rdump [ options [ arguments ] ] filename ...
dump backs up all files in filesystem, or files changed after a certain
date, or a specified set of files and directories, to magnetic tape,
diskettes, or files. options is a string that specifies dump options,
as shown below. 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 dump is called as rdump, the dump device defaults to
If no options are given, the default is 9u.
dump is normally used to back up a complete filesystem. To restrict
the dump to a specified set of files and directories on one filesystem,
list their names on the command line. In this mode the dump level is
set to 0 and the u option is ignored.
0-9 The "dump level." All files in the filesystem that have been
modified since the last dump at a lower dump level are copied to
the volume. For instance, if you did a "level 2" dump on Mon-
day, followed by a "level 4" dump on Tuesday, a subsequent
"level 3" dump on Wednesday would contain all files modified or
added since the "level 2" (Monday) backup. A "level 0" dump
copies the entire filesystem to the dump volume.
Create a dump table-of-contents archive in the specified file,
archive-file. This file can be used by restore(8) to determine
whether a file is present on a dump tape, and if so, on which
volume it resides. For further information on the use of a dump
archive file, see restore(8).
Blocking factor. Specify the blocking factor for tape writes.
The default is 20 blocks per write. Note: the blocking factor
is specified in terms of 512 bytes blocks, for compatibility
with tar(1). The default blocking factor for tapes of density
6250 BPI and greater is 64. The default blocking factor for
cartridge tapes (c option specified) is 126. The highest block-
ing factor available with most tape drives is 126.
c Cartridge. Use a cartridge instead of the standard half-inch
reel. This sets the density to 1000 BPI, the blocking factor to
126, and the length to 425 feet. This option also sets the
"inter-record gap" to the appropriate length. When cartridge
tapes are used, and this option is not specified, dump will
slightly miscompute the size of the tape. If the b, d, s or t
options are specified with this option, their values will over-
ride the defaults set by this option.
d bpi Tape density. The density of the tape, expressed in BPI, is
taken from bpi. This is used to keep a running tab on the
amount of tape used per reel. Default densities are:
1/2" tape 1600 BPI
1/4" cartridge 1000 BPI
2.3-Gbyte 8mm tape 54,000 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). Note: the density
specified should correspond to the density of the tape device
being used, or dump will not be able to handle end-of-tape prop-
erly. The d option is not compatible with the D option.
D Diskette. Specify diskette as the dump media.
Dump file. Use dump-file as the file to dump to, instead of
/dev/rmt8. If dump-file is specified as `-', dump to the stan-
dard output. If the file name argument is of the form
machine:device, dump to a remote machine. Since dump is nor-
mally run by root, the name of the local machine must appear in
the .rhosts file of the remote machine. If the file name argu-
ment is of the form user@machine:device, dump will attempt to
execute as the specified user on the remote machine. The speci-
fied user must have a .rhosts file on the remote machine that
allows root from the local machine. If dump is called as rdump,
the dump device defaults to dumphost:/dev/rmt8. To direct the
output to a desired remote machine, set up an alias for dumphost
in the file /etc/hosts.
n Notify. When this option is specified, if dump requires atten-
tion, it sends a terminal message (similar to wall(1)) to all
operators in the "operator" group.
s size Specify the size of the volume being dumped to. When the speci-
fied size is reached, dump waits for you to change the volume.
dump interprets the specified size as the length in feet for
tapes, and cartridges and as the number of 1024 byte blocks for
diskettes. The following are defaults:
1/2" tape 2300 feet
60-Mbyte 1/4" cartridge 425 feet
150-Mbyte 1/4" cartridge 700 feet
2.3-Gbyte 8mm 6000 feet
diskette 1422 blocks (Corresponds to a
1.44-Mbyte diskette, with one
cylinder reserved for bad block
Specify the number of tracks for a cartridge tape. The t option
is not compatible with the D option. The following are
60-Mbyte 1/4" cartridge (Sun2 only) 4 tracks
60-Mbyte 1/4" cartridge (all other platforms)
150-Mbyte 1/4" cartridge 18 tracks
u Update the dump record. Add an entry to the file /etc/dump-
dates, for each filesystem successfully dumped that includes the
filesystem name, date, and dump level. This file can be edited
by the super-user.
v After writing each volume of the dump, the media is rewound and
is verified against the filesystem being dumped. If any dis-
crepancies are found, dump will respond as if a write error had
occurred; the operator will be asked to mount new media, and
dump will attempt to rewrite the volume. Note that any change
to the filesystem, even the update of the access time on a file
will cause the verification to fail. Thus, the verify option
can only be used on a quiescent filesystem.
w List the filesystems that need backing up. This information is
gleaned from the files /etc/dumpdates and /etc/fstab. When the
w option is used, all other options are ignored. After report-
ing, dump exits immediately.
W Like w, but includes all filesystems that appear in /etc/dump-
dates, along with information about their most recent dump dates
and levels. Filesystems that need backing up are highlighted.
/dev/rmt8 default unit to dump to
dumphost:/dev/rmt8 default remote unit to dump to if called as rdump
/dev/rst* Sun386i cartridge tape dump device
/dev/rfd0a Sun386i 1.44 megabyte 3.5-inch high density
diskette drive dump device
/dev/rfdl0a Sun386i 720 kilobyte 3.5-inch low density diskette
drive dump device
/dev/rfd0c Sun386i 1.44 megabyte 3.5-inch high density
diskette drive dump device
/dev/rfdl0c Sun386i 720 kilobyte 3.5-inch low density diskette
drive dump device
/etc/dumpdates dump date record
/etc/fstab dump table: file systems and frequency
/etc/group to find group operator
bar(1), fdformat(1), tar(1), wall(1), dump(5), fstab(5), restore(8),
While running, dump emits many verbose messages.
0 Normal exit.
1 Startup errors encountered.
3 Abort - no checkpoint attempted.
Fewer than 32 read errors on the file system 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 is recommended that incremental dumps also be performed with the
system running in single-user mode.
dump does not support multi-file multi-volume tapes.
Here are some examples of arguments which produce satisfactory results
on a number of typical tape drives. Note that individual options can
be in any order; however, the position of each following argument
depends on the relative position of each option.
60-MByte cartridge (Sun2 only): dump cdst 1000 425 4
60-MByte cartridge: dump cdst 1000 425 9
150-MByte cartridge: dump cdst 1000 700 18
1/2" tape: dump dsb 1600 2300 126
2.3-GByte 8mm tape: dump dsb 54000 6000 126
To make a full dump of a root filesystem on sd3, on a 150-MByte car-
tridge tape st0, use:
dump 0cdstfu 1000 700 18 /dev/rst0 /dev/sd3a
To make and verify an incremental dump at level 5 of the usr partition
of sd3, on a 1/2" reel tape st1:
dump 5dsbfuv 1600 2300 126 /dev/rst1 /dev/sd3g
To make a full backup of the entire disk sd3, on a 2.3-GByte 8mm tape
dump 0dsbfu 54000 6000 126 /dev/rst2 /dev/sd3c
dump requires operator intervention on these conditions: end of volume,
end of dump, volume write error, volume 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 option, 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, as appropriate.
Since backing up a disk can involve a lot of time and effort, dump
checkpoints at the start of each volume. If writing that volume fails
for some reason, dump will, with operator permission, restart itself
from the checkpoint after a defective volume has been replaced.
dump reports periodically, and in verbose fashion. Each report
includes estimates of the percentage of the dump completed and how long
it will take to complete the dump. The estimated time is given as
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(8). 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. How-
ever 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 occur-
rence), 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
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
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.
Process Priority of dump
dump uses multiple processes to allow it to read from the disk and
write to the media concurrently. Due to the way it synchronizes
between these processes, any attempt to run dump with a nice (process
priority) of `-5' or better will likely make dump run slower instead of
7 October 1990 DUMP(8)