vxdump(1M) (VxFS) vxdump(1M)
NAME
vxdump - incremental file system dump
SYNOPSIS
/usr/lib/fs/vxfs/vxdump [options] filesystem
DESCRIPTION
vxdump back up all files in filesystem, or files changed after a cer-
tain date, to an output device or file; options is a string that
specifies vxdump options, as shown below; filesystem is a character
special device (for example, /dev/ios0/rsdisk000s4) or a mount point
for a file system (for example, /usr).
If no options are given, the default is 9-u and the default output
device is assumed to be a 2400 foot, 6250 bpi 9-track tape.
If the -c option is specified, the output device is assumed to be a
QIC-320 cartridge tape.
If the -D option is specified, the output device is assumed to be a
DAT (Digital Audio Tape) device.
Options -c, -d, -D, and -s are only used to calculate tape size. The
-M option is used to specify megabytes per tape, and may be used with
any type of tape. The -M option is much simpler than the above
options, provided the tape capacity is known.
vxdump does not handle EOT (end of tape) gracefully. Unlike other
backup utilities, such as cpio, that detect the EOT and then prompt
the user to insert another tape before continuing the backup, vxdump
will issue a write error upon reaching the EOT and will attempt to
restart the backup. It is, therefore, important to supply vxdump with
accurate information about the tape capacity with the -M option, or
about tape type, density, and length. This will allow vxdump to deter-
mine how much data to write to each tape before asking for the next
tape. (See EXAMPLES below.) Since vxdump doesn't handle EOT, it is
important to be aware that if you over-estimate how much data fits on
the tape, the last of the multiple dumps on the tape will be incom-
plete. You can store multiple dumps on one tape by writing to the no-
rewind device, although you may need to restart the last dump when it
hits EOT.
Example:
vxdump 0uf /dev/ios0/rstape000hn /usr
vxdump 0uf /dev/ios0/rstape000h /
The above commands write a level 0 dump of /usr and a level 0 dump of
/ (root) to the same tape. Notice the use of the no-rewind device in
the dump of /usr. Multiple dumps can be recovered using the -s option
in vxrestore(1M).
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Use the following guidelines, keeping in mind that file systems with
many small files (<2 KB) will use more tape, and that use of the -M
option is recommended in lieu of other options which determine tape
size (-c, -d, -D, and -s):
Tape Mode Type Length Capacity
________________________________________________
9-track - 2400 6250ft ~140 MB
9-track - 2400 1600ft ~25 MB
Streamer:
QIC-320 - 600 - ~120 MB
QIC-120 - 120M 620ft ~105 MB
QIC-150 - 150M 620ft ~135 MB
QIC-525 - 525M 620ft ~475 MB
DAT/DDS-1 - - 60m ~1200 MB
DAT/DDS-1 - - 90m ~1800 MB
DAT/DDS-2 - - 120m ~3600 MB
8mm Tape EXB-8200 - 15m ~265 MB
(Exabyte) EXB-8500 - 15m ~530 MB
Notes:
- EXB-8200 and EXB-8500 are different write densities for working
with 8 mm tapes (low- and high-density).
- If a "device with compression" is being used (e.g.
/dev/ios0/rstape004c), this increases the capacity by a factor of
1.6 - 2.0 (maximum).
- The capacity of all "tapes" is approx. 10% below the specified
sizes (e.g. 150 MB streamer can record approx. 135 MB data). The
reduction in the specified value takes into account any tape errors
and automatic tape leader for lower transfer rates.
- Specific details on all tape types (e.g. how a 150 MB streamer
behaves in a 525 MB streamer drive) can be found in the TAPE NOTES
for stape(7).
OPTIONS
0-9 Dump level. All files in the filesystem that have been modified
since the last vxdump at a lower dump level are copied to the
volume. For instance, if you did a level 2 dump on Monday, fol-
lowed 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.
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-b factor
Blocking factor. Specifies the blocking factor for tape writes.
The default is 64 blocks per write. A tape block is 512 bytes.
Note that the blocking factor must be a multiple of 4.
-c Cartridge. Uses a QIC-320 instead of the standard half-inch reel.
The length is set to 560 feet. This option is incompatible with
the -d and -s options. If the tape capacity is known, the -M
option is recommended instead of the -c option.
-d bpi
Tape density. Meaningful only for 9-track tapes. The density of
the tape, expressed in bits per inch, is taken from bpi. This is
used to keep a running tab on the amount of tape used per reel.
The default density is 6250.
-D mins
DAT. Uses DAT (Digital Audio Tape) instead of the standard half-
inch reel. mins is the number of minutes on the DAT tape. This
option is incompatible with the -d and -s options.
-f dump-file
Dump file. Uses dump-file as the output device or file to dump
to, instead of the default (/dev/rmt8). If dump-file is specified
as -, dump to the standard output. Note that dump-file can be the
name of a disk file (for example, /tmp/dump.output). This creates
a dump image on disk. This can then be restored (for example,
vxrestore xuf /tmp/dump.output), and transferred to another sys-
tem or written to tape using another utility, such as cpio.
-M megabytes
Maximum amount of data to write to each tape, given in megabytes
(10E6). This option determines the maximum amount of data to
write to each tape before vxdump will ask for another tape. This
can be used with QIC, DAT, 9-track, or any type of tape device.
The maximum megabytes specified should be somewhat less than the
capacity of the tape, to allow for retries on bad sections of
tape. This option overrides the -c, -d, -D, and -s options.
-n Notifies all operators in the operator group that vxdump requires
attention by sending messages to their terminals, in a manner
similar to that used by the wall command.
-s size
Specifies the size (in feet) of the volume being dumped to. When
the specified size is reached, vxdump waits for you to change the
volume. The default size for 9-track tape is 2300 (feet), which
is slightly less than the actual physical size of the tape. This
allows for bad sectors on the tape and guards against tape over-
run.
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-t tracks
Specifies the number of tracks for a cartridge tape. The default
is 9 tracks. The -t option is not compatible with the -D option.
-u Updates the dump record. For each file system successfully
dumped, adds an entry to the file /etc/dumpdates, that includes
the file system name, date, and dump level. This file can be
edited by the superuser.
-W The -W option lists all file systems that appear in
/etc/dumpdates and /etc/fstab, along with information about their
most recent dump dates and levels. If the -W option is set, all
other options are ignored, and vxdump exits immediately.
EXAMPLES
The following examples describe possible command lines using vxdump
options:
vxdump 0u /usr
Perform a level 0 dump of /usr to /dev/rmt8, which is a 6250 bpi
9-track tape drive with a 2400 foot tape mounted on it; update
/etc/dumpdates.
vxdump 0Muf 320 /dev/rmt8 /usr
Perform a level 0 dump of /usr to /dev/rmt8, which writes a max-
imum of 320 MB to each tape before asking for the next tape. The
type of tape device does not matter, but you must know the tape
capacity.
vxdump 0udf 1600 /dev/rmt0 /usr
Perform a level 0 dump of /usr to /dev/rmt0, which is a 1600 bpi
9-track tape drive with a 2400 foot tape mounted on it; update
/etc/dumpdates.
vxdump 0usf 1200 /dev/ios0/rstape001h /usr
Perform a level 0 dump of /usr to /dev/ios0/rstape001h, which is
a 6250 bpi 9-track tape drive with a 1200 foot tape mounted on
it; update /etc/dumpdates.
vxdump 2ucf /dev/ios0/rstape000 /home
Perform a level 2 dump of /home to /dev/ios0/rstape000, which is
a QIC-320 cartridge tape; update /etc/dumpdates.
vxdump 0Df 120 /dev/ios0/rstape000 /usr
Perform a level 0 dump of /usr to /dev/ios0/rstape000, which is a
DAT 60-meter (120 minute) tape; do not update /etc/dumpdates.
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NOTES
Fewer than 32 read errors on the file system are ignored.
Each tape requires a new process, so parent processes for tapes
already written just hang around until the entire archive is written.
It is recommended that incremental dumps also be performed with the
system running in singleuser mode.
For a multiple-tape dump. always use tapes of exactly the same capa-
city, to avoid hitting EOT on a shorter tape.
For simplicity, if the tape size in megabytes is known, the -M option
is recommended, instead of the -c, -d, -D, or -s options.
If you do multiple dumps to a "no-rewind" tape device file, the max-
imum capacity to write to each tape will not protect vxdump from even-
tually hitting EOT. This may require that you restart the last
(failed) dump on a new tape.
SECURITY NOTES
Only a superuser can do a dump of a file system. This prevents users
from being able to gain access to files with selective read permis-
sions.
There are special considerations for specifying the remote username in
the dump-file to the -f option. In order to specify a user other than
the one who invoked the remote dump or restore utility, the user who
invoked the utility must have permission from the remote user. This is
accomplished by making the appropriate entry in the .rhosts file which
resides in the remote user's home directory. The entry should include
the originating hostname and username (which will always be "root"
since only a superuser can dump a file system).
In addition to the normal security checks. the security parameters can
affect the use of the remote dump and restore utilities.
If the AUTOLOGINMINUID parameter is set to a positive number on the
remote host system, then users with user ids less than that number
cannot use automatic remote access.
If the DISABLERHOSTS parameter is set to "yes" on the remote host
system, then any .rhosts files will be ignored on the remote host sys-
tem. If the DISABLERHOSTS parameter is set to "no" on the remote host
system, then any .rhosts files must be writable only by the owner.
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NOTES
The -s option should not be used with the -c option. If these options
are used together, the number of feet specified will be multiplied by
4 resulting in erroneous capacities per tape.
vxdump does not gracefully handle EOT.
FILES
/dev/rmt8
default device to dump to
/etc/dumpdates
dump date record
/etc/group
to find group operator
SEE ALSO
tar(1), shutdown(1M), vxrestore(1M), wall(1M).
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