dump, rdump - Performs incremental file system dumps
/usr/sbin/dump [key[argument...] file system]
/usr/sbin/rdump -fdump_file [otherkey[argument...]file system]
Specifies the dump level. All files modified since the last time-stamp
whose names are currently stored in the /etc/dumpdates file for a named
file system at levels less than the one specified are dumped to tape.
When no time-stamp entry is defined for a dump level, the Epoch is
assumed; thus, the value -0 for this key causes the entire file system
to be dumped to the storage medium.
Specifies the number of blocks in 1024 bytes to write to the storage
medium. The default write block value is 10 blocks (or 10 kilobytes).
In many instances, increasing the number of blocks per write will
increase your dump performance. For optimal results on Compaq's plat-
form, use a value that is greater than or equal to 32, is a multiple of
4, and is less than 65.
-c The dump medium is a not a 9-track cartridge tape.
Specifies the write density of the storage medium. The density operand
is expressed in bits per inch (bpi). This information is used in calcu-
lating the amount of medium used per each volume of the storage medium.
For the dump command, the density will be automatically provided by
Compaq base system supported devices. Otherwise, the default write
density for the dump and rdump commands is 1600 bpi.
Writes the dump to the dump_file storage device instead of the default
tape drive. When the name of dump_file is - (dash), the dump process
writes to standard output. When the name of the dump_file is
/dev/ntape/tape?*, the dump process will enable the -N option. When the
rdump command is invoked, the dump_file operand must specify both the
remote machine and the storage device in the format
[user@]machine:device, where where user is an optional user identifica-
tion (account) used to logon to the machine. If you do not specify
user rdump will use the user identification from the current process.
The machine is the name or reference designation of the host machine,
and device is the name or reference designation of the storage device.
If you want to specify an IPv6 address for machine, you must prefix the
address with the \[ (backslash, left bracket) characters and terminate
the address with the \] (backslash, right bracket) characters. Because
the bracket characters are shell metacharacters, your must precede them
with the backslash character.
Specifies the label of the dump to be displayed during restoration.
The default label is "No Label". The label can be a maximum of 16
-n Notifies, by means of a command similar to wall(1), all operators in
the group named operator, which is specified in the /etc/group file
whenever dump or rdump requires operator attention (to change a tape,
Specifies the size of a dump tape. The size operand is expressed in
feet. When the amount of tape specified by size has been written,
either process waits for the current reel to be changed (see the -n
option). For the dump command, the tape size will be automatically pro-
vided by Compaq base system supported devices. Otherwise, the default
tape size for the dump and rdump commands is 2300 feet.
-u Writes the time of the beginning of the dump as the time-stamp entry in
the /etc/dumpdates file for the file system record when the dump suc-
-w Tells an operator what file systems must be dumped to the storage dev-
ice. This information is obtained from the /etc/dumpdates and
/etc/fstab files. The -w key tells either process to print to the
standard output a record for each file system listed in the
-B Specifies a block-mode device. For the dump command, the estimated
calculations will be based on the device's storage capacity instead of
density and size.
-E Prints the estimated size of the dump file in 1-kilobyte blocks and the
estimated number of volumes that make up the dump file, only. The dump
file will be opened and closed, but nothing will be written to it. The
information will be output through standard error and will have a for-
mat like the following:
23382 blocks, 0.04 volumes
If the dump file is on disk, the format will be:
The operand placement will be preserved, but the exact words "blocks,"
and "volumes" are not guaranteed. Refer to the EXAMPLES section for
-N Disables the rewinding of the tape and placing the tape unit off line
after completing the dump session. By default, when the dump command
finishes backing up a file system it rewinds the tape and takes it off
line. For some tape subsystems, this tape will be ejected from the
unit. The -N option is the default when the dump_file operand is
/dev/ntape/tape?. If you use the -N option to dump to a regular file
that does not have the letters "rm" in its name, dump will inform you
of your error in using -N and terminate.
Specifies output file size in feet. When the -B option is used, the
full_tape_size operand specifies the output file size in number of
Specifies a tape number, which is used in the dialog with the operator
as the number of the first tape.
-V Prevents any extended attributes from being archived with associated
-W Similar to -w, but for any file system listed in the /etc/dumpdates
file, prints an output record and highlights this record with the >>
(greater than) character, all files that must be dumped. When -W is
specified, all other options are ignored and dump exits immediately.
The dump command copies to the default /dev/tape/tape0_d0, or to the alter-
nate storage device specified with the -f option, all files and any associ-
ated extended attributes (including ACLs, see the acl(4) and proplist(4)
reference pages) changed after a certain date in the specified local file
The rdump command copies to the dump_file storage device all files and any
associated extended attributes (including ACLs, see the acl(4) and pro-
plist(4) reference pages) changed after a certain date in the specified
These commands cannot be used to archive AdvFS filesets. See vdump(8) for
the operations used to archive AdvFS filesets.
The dump and rdump commands are used to dump local files and any associated
local attributes from a single file system defined by the file system
operand to a local or remote storage device, respectively, where file sys-
tem contains the files you want to back up.
The dump and rdump commands perform similar functions with respect to
storage of files contained in the named file system. However, the rdump
command requires that the -f option be used with any otherkey and the spe-
cial dump_file operand.
Both commands copy all files in file system whose dump level is less than a
specified value, and that have changed after a specified date to the
default storage device or to an alternate storage device. The dump level
and date are specified in the local /etc/dumpdates file. The key and argu-
ment operand specify one or more options that may be used to write files to
the storage medium. Characters permitted by the key operand are similar to
options that consist of any of the characters 0123456789bcdfnsuwBNSTW only,
which may be used in any logical combination, but must be preceded with the
- (dash) character; the argument operand specifies other options that tell
these dump and rdump processes what to do. These options are described in
the OPTIONS section. Not all keys permit argument options to be specified.
The /etc/dumpdates file consists of 3-column record lines that specify the
file system name, a dump level, and a standard time-stamp. These processes
enter a time-stamp into the file system record after each file in the named
file system is successfully backed up. The 3-column record in the
/etc/dumpdates file contains the following information:
1 File system name
Lists the file system device name.
2 Dump level
This is an integer between 1 and 9 that defines a hierarchy for files
in file system. This hierarchy indicates which files should be written
to the storage medium when the dump or rdump command is executed.
Level 0 defines all the files in file system. When a level is
assigned, all files equal to and less than that level in file system
are backed up.
The time-stamp tells the dump or rdump process when file system had its
last backup. This time-stamp is written by the dump or rdump process
after the specified file system backup is completed. When there is no
time-stamp, the dump or rdump process assumes the beginning of time
(called the Epoch).
The /etc/dumpdates file is written in ASCII and consists of a single record
per line. This file may be edited to change any record field, when neces-
Either process requires operator intervention when any of the following
conditions occur: end-of-tape, end-of-dump, tape-write error, tape-open
error, or when the number of disk-read errors is greater than 32. In addi-
tion to alerting all operators specified by the -n key, these processes
interact with an operator at the terminal from which dump or rdump was
invoked when either program can no longer proceed.
All queries written to standard output by the dump or rdump process must be
answered by typing yes or no on the invoking terminal.
Because a dump to any storage medium requires excessive time to process,
each process checks itself at the start of each storage volume. In many
instances, the default dump performance can be improved by modifying the
number of blocks per write. For additional information, see the descrip-
tion for the -b switch in the OPTIONS section.
When a volume write fails, dump or rdump restarts itself from the last suc-
cessful checkpoint, with operator permission, after the currently written
storage medium is properly removed and another (replacement) storage medium
has been mounted.
These processes also tell an operator what is going on at periodic inter-
vals when writing to the storage medium. This information consists of
somewhat conservative estimates for the number of blocks to write, the
number of storage media that must be used for the dump, the time to com-
plete the dump, and the time until the storage medium must be replaced with
another one to complete the dump. Output is verbose, so that others know
that the terminal controlling dump is busy. When processing takes place,
the following conditions apply:
+ Fewer than 32 read errors during a dump or rdump tape-dump process are
ignored. Each renewal of the storage medium requires a new dump pro-
cess, so that parent processes for storage media already written are
in effect until the entire storage medium is written.
+ When the dump command has the W or w key set, no records are written
to the standard output for a file system that has no current record in
the /etc/dumpdates file, even when listed in the /etc/fstab file.
+ When no argument is specified, the key operand is assumed to be -9u so
that the default file system is dumped to a default storage medium
named /dev/tape/tape0_d0 (usually a tape).
The dump command copies to the default /dev/tape/tape0_d0, or to the alter-
nate storage device specified with the -f option, all files changed after a
certain date in the specified local file system.
The rdump command copies to the dump_file storage device all files changed
after a certain date in the specified file system. This command is similar
in operation to dump, except that the -f option is always specified (see
the OPTIONS section) together with any otherkey you may wish to specify.
The dump_file operand should always be specified by machine name and device
name as machine:device name. If you want to specify an IPv6 address for
machine, you must prefix the address with the \[ (backslash, left bracket)
characters and terminate the address with the \] (backslash, right bracket)
The rdump command starts remote server /usr/sbin/rmt or /etc/rmt on the
client machine to access the storage medium.
Another vendor's rdump command may fail because rmt is not located in /etc.
To avoid this problem, it may be necessary to provide a symbolic link on
the machine pointing to /usr/sbin/rmt, as shown in the following example:
ln -s /usr/sbin/rmt /etc/rmt
Although the rdump command can detect magnetic tape on remote ULTRIX and
Tru64 UNIX systems, it cannot detect magnetic tape on other remote systems.
Instead, it defaults to treating the output medium as a disk file and
aborts the operation should it encounter overflow or I/O error cases.
Remote systems must be able to run the uname command if you are to use the
rdump command. If a remote system cannot run the uname command, you can set
the environment variable OSF_RDUMP_SIMP_RCMD before you attempt the opera-
1. Estimates for dump and rdump.
The information in this note is specific to Compaq tape devices and
the densities and sizes they use under rdump. The size and density
information is used to estimate the number of volumes required for the
current dump or rdump request. Some of the factors that will effect
the estimate calculation include the following:
+ Track format
+ Interrecord gap size
+ Writing optimization technologies
+ Appending to a tape
The estimate calculation does not take these factors into account and
can result in very large (100-500%) miscalculations. The estimates
can be customized by adjusting the size in feet (-s) or size in 1024-
byte block (-BS) variables to the desired results. The default values
for /dev/tape/tape?_d0 devices used in the dump estimate calculation
are shown in the following table:
Tape Device Density Size Size
TA78 6250 1925 141056
TA79 6250 1925 141056
TA81 6250 1925 141056
TA90 38000 436 194560
TA91 38000 436 194560
TF30 6667 1182 92416
TF70 10000 2457 287948
TF70L 10000 2457 287948
TK50 6667 1182 92416
TK70 10000 2457 287948
TKZ09 54000 7456 4718592
TLZ04 61000 1584 1132646
TLZ06 61000 2640 1887436
TLZ07 61000 2640 1887436
TS05 1600 2075 38912
TU77 1600 2075 38912
TU78 1600 2075 38912
TU80 1600 2075 38912
TU81 1600 2075 38912
TU81E 1600 2075 38912
TZ05 1600 2075 38912
TZ07 1600 2075 38912
TZ30 6667 1182 92416
TZ85 42500 4925 2453299
TZ857 42500 4925 2453299
TZK08 54000 3276 2073600
TZK10 16000 2580 483840
2. The rdump command starts the remote server /usr/sbin/rmt on the client
machine to access the storage medium. If the rdump command cannot
find /usr/sbin/rmt, it will try /etc/rmt and rmt.
3. The rdump program can detect remote tape support on Tru64 UNIX and
ULTRIX systems. However, due to the lack of a standard for UNIX mag-
netic tape functions, it cannot utilize remote tape support on other
systems. This means that multivolume dumpsets can only be created when
the remote system is Tru64 UNIX, DEC OSF/1 (the former name of Tru64
UNIX), or ULTRIX, or if there is embedded multivolume support in the
remote system (such as is the case with VMS, where support is in the
Magtape ACP). For rare cases where the remote system is non-UNIX,
compatibility may require that rdump not use UNIX-like commands. In
order to obtain this behavior, the user or system manager should use
the following command:
The previous command can be used on a system wide (global) or per
rdump command basis.
4. For proper operation, the server's /.rhosts file must contain the name
or reference designation of the client's machine.
5. The rdump and the dump commands do not handle MFS or AdvFS filesys-
6. After encountering tape write errors, dump or rdump queries the opera-
tor about performing a rewrite. If the operator requests a rewrite, a
rewind is performed, followed by an attempt to rewrite the data. In
the event the no-rewind device is used, the user should always load a
new tape to avoid the possibility of overwriting previously written
The dump and rdump commands exit with 0 status on success. Startup errors
are indicated with an exit code of 1; abnormal termination is indicated
with an exit code of 3.
1. To perform a full level 0 dump, enter a command similar to the follow-
dump -0un -f /dev/tape/tape1_d0 -b 32 /fs1
In this example, 0 specifies that all files in the file system fs1
will be dumped to /dev/tape/tape1_d0; u specifies dump to update the
/etc/dumpdates file after a successful dump of the file system; and n
specifies that operators will be notified. The estimate calculation
will be based upon the tape device defaults. The write block size is
set to 32 kilobytes.
2. To dump a local file system to a remote storage tape, enter a command
similar to the following:
rdump -3u -f tape_server:/dev/tape/tape1_d0 /fs1
In this example, 3 specifies the dump level of all files in the file
system /fs1 that will be dumped to tape /dev/tape/tape1_d0 on system
tape_server, and u specifies the dump to update the /etc/dumpdates
file after a successful dump of the file system. The estimated calcu-
lation will be based on the rdump defaults. The write block size will
be the default.
3. To obtain an estimated number of blocks and volumes for the current
dump session, enter the following:
dump -0Ef /dev/tape/tape1_d0 /usr
The system displays output similar to the following:
358696 blocks, 0.19 volumes
4. The following examples show alternative ways of scheduling backups.
Select the backup schedule that best fits your needs.
a. 7-day incremental schedule
The following schedule is a 7-day incremental schedule. This
schedule is useful for small-to-medium storage systems. The
basic algorithm is n, n+1, ... The number of dump files to per-
form a full restore can vary from 1 to 7. The following is an
example of a 28-day schedule:
0 1 2 3 4 5 6
0 1 2 3 4 5 6
0 1 2 3 4 5 6
0 1 2 3 4 5 6
b. 7-day alternative differential schedule
The following schedule is a 7-day alternative differential
schedule. This schedule is useful for small-to-medium storage
systems. The basic algorithm is n-1, n+3, ... The number of
dump files to perform a full restore can vary from 1 to 4. The
following is an example of a 28-day schedule:
0 5 4 7 6 9 8
0 5 4 7 6 9 8
0 5 4 7 6 9 8
0 5 4 7 6 9 8
c. 28-day alternative differential schedule
The following schedule is a 28-day alternative differential
schedule. This schedule is useful for small-to-large storage
systems. The algorithm combines the 7-day incremental and the
7-day alternative differential schedules. The number of dump
files to perform a full restore can vary from 1 to 7. The fol-
lowing is an example of a 28-day schedule:
0 5 4 7 6 9 8
1 5 4 7 6 9 8
2 5 4 7 6 9 8
3 5 4 7 6 9 8
This schedule limits full dumps to once a month. Therefore, it
is possible to lose a month's worth of data. Alternative
approaches to address this problem might include duplicating the
full tape or doing full backups twice a month instead of once a
The dump command path in single user mode.
The dump command path in multiuser mode.
Used by the rdump remote tape access program.
Contains a list of file systems that were backed up, the date that each
file system was backed up, and the backup level.
Commands: restore(8), rrestore(8), rmt(8)
Files: acl(4), proplist(4)