ufsdump(1M) manual page
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ufsdump - incremental file system dump
/usr/sbin/ufsdump
[options] [arguments] files_to_dump
SUNWcsu
ufsdump
backs up all files specified by files_to_dump (normally either a whole
file system or files within a file system changed after a certain date)
to magnetic tape, diskette, or disk file. When running ufsdump, the file
system must be inactive; otherwise, the output of ufsdump may be inconsistent
and restoring files correctly may be impossible. A file system is inactive
when it is unmouned or the system is in single user mode. A file system
is not considered inactive if one tree of the file system is quiescent
while another tree has files or directories being modified.
options is a
single string of one-letter ufsdump options.
arguments may be multiple strings
whose association with the options is determined by order. That is, the
first argument goes with the first option that takes an argument; the
second argument goes with the second option that takes an argument, and
so on.
files_to_dump is required and must be the last argument on the command
line. See OPERANDS for more information.
With most devices ufsdump can automatically
detect the end-of-media. Consequently, the d, s, and t options are not necessary
for multi-volume dumps, unless ufsdump does not understand the way the device
detects the end-of-media, or the files are to be restored on a system with
an older version of the restore command.
The following options are
supported:
- 0-9
- The ‘dump level.’ All files specified by files_to_dump that
have been modified since the last ufsdump at a lower dump level are copied
to the dump_file destination (normally a magnetic tape device). For instance,
if a ‘level 2’ dump was done on Monday, 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 file system to the dump_file.
- a archive_file
- Archive file. Archive
a dump table-of-contents in the specified archive_file to be used by ufsrestore(1M)
to determine whether a file is in the dump file that is being restored.
- b factor
- Blocking factor. Specify the blocking factor for tape writes. The
default is 20 blocks per write for tapes of density less than 6250BPI
(bytes-per-inch).
The default blocking factor for tapes of density 6250BPI
and greater is
64. The default blocking factor for cartridge tapes (c option) is 126. The
highest blocking factor available with most tape drives is 126. Note: the
blocking factor is specified in terms of 512-byte blocks, for compatibility
with tar(1)
.
- c
- Cartridge. Set the defaults for cartridge instead of the standard half-inch
reel. This sets the density to 1000BPI
and the blocking factor to 126. Since
ufsdump can automatically detect the end-of-media, only the blocking parameter
normally has an effect. When cartridge tapes are used, and this option is
not specified, ufsdump will slightly miscompute the size of the tape. If
the b, d, s or t options are specified with this option, their values will
override the defaults set by this option.
- d bpi
- Tape density. Not normally
required, as ufsdump can detect end-of-media. This parameter can be used to
keep a running tab on the amount of tape used per reel. The default density
is 6250BPI
except when the c option is used for cartridge tape, in which
case it is assumed to be 1000BPI
per track. Typical values for tape devices
are:
- 1/2" tape
- 6250 BPI
- 1/4" cartridge
- 1000 BPI
The tape densities and
other options are documented in the st(7D)
man page.
- D
- Diskette. Dump to
diskette.
- f dump_file
- Dump file. Use dump_file as the file to dump to, instead
of /dev/rmt/0. If dump_file is specified as -, dump to standard output.
- If
the name of the file is of the form
- machine:device, the dump is done from
the specified machine over the network using rmt(1M)
. Since ufsdump is normally
run by root, the name of the local machine must appear in the /.rhosts file
of the remote machine. If the file is specified as user@machine:device,
ufsdump 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
the user invoking the command from the local machine to access the remote
machine.
- l
- Autoload. When the end-of-tape is reached before the dump is complete,
take the drive offline and wait up to two minutes for the tape drive to
be ready again. This gives autoloading (stackloader) tape drives a chance
to load a new tape. If the drive is ready within two minutes, continue. If
it is not, prompt for another tape and wait.
- n
- Notify all operators in the
sys group that ufsdump requires attention by sending messages to their
terminals, in a manner similar to that used by the wall(1M)
command. Otherwise,
such messages are sent only to the terminals (such as the console) on
which the user running ufsdump is logged in.
- o
- Offline. Take the drive offline when the dump is complete or the end-of-media
is reached and rewind the tape, or eject the diskette. In the case of some
autoloading 8mm drives, the tape is removed from the drive automatically.
This prevents another process which rushes in to use the drive, from inadvertently
overwriting the media.
- s size
- Specify the size of the volume being dumped to. Not normally required,
as ufsdump can detect end-of-media. When the specified size is reached, ufsdump
waits for you to change the volume. ufsdump interprets the specified size
as the length in feet for tapes and cartridges, and as the number of 1024-byte
blocks for diskettes. The values should be a little smaller than the actual
physical size of the media (for example, 425 for a 450-foot cartridge). Typical
values for tape devices depend on the c option, for cartridge devices,
and the D option for diskettes:
- 1/2" tape
- 2300 feet
- 60-Mbyte 1/4" cartridge
- 425 feet
- 150-Mbyte 1/4" cartridge
- 700 feet
- diskette
- 1422 blocks (Corresponds
to a 1.44-Mbyte diskette, with one cylinder reserved for bad block information.)
- S
- Size estimate. Determine the amount of space that is needed to perform
the dump without actually doing it, and display the estimated number of
bytes it will take. This is useful with incremental dumps to determine how
many volumes of media will be needed.
- t tracks
- Specify the number of tracks
for a cartridge tape. Not normally required, as ufsdump can detect end-of-media.
The default is 9 tracks. The t option is not compatible with the D option.
Values for Sun-supported tape devices are:
- 60-Mbyte 1/4" cartridge
- 9 tracks
- 150-Mbyte 1/4" cartridge
- 18 tracks
- u
- Update the dump record. Add an entry
to the file /etc/dumpdates, for each file system successfully dumped that
includes the file system name, date, and dump level.
- v
- Verify. After each
tape or diskette is written, verify the contents of the media against the
source file system. If any discrepancies occur, prompt for new media, then
repeat the dump/verification process. The file system must be unmounted.
This option cannot be used to verify a dump to standard output.
- w
- Warning.
List the file systems that have not been backed up within a day. This information
is gleaned from the files /etc/dumpdates and /etc/vfstab. When the w option
is used, all other options are ignored. After reporting, ufsdump exits immediately.
- W
- Warning with highlight. Similar to the w option, except that the W option
includes all file systems that appear in /etc/dumpdates, along with information
about their most recent dump dates and levels. File systems that have not
been backed up within a day are highlighted.
The following operand
is supported:
- files_to_dump
- Specifies the files to dump. Usually it identifies
a whole file system by its raw device name (for example, /dev/rdsk/c0t3d0s6).
Incremental dumps (levels 1 to 9) of files changed after a certain date
only apply to a whole file system. Alternatively, files_to_dump can identify
individual files or directories. All files or directories are dumped, which
is equivalent to a level 0 dump; however, /etc/dumpdates is not updated,
even with the u option specified. In all cases, the files must be contained
in the same file system, and the file system must be local to the system
where ufsdump is being run.
files_to_dump is required and must be the last
argument on the command line.
If no options are given, the default is 9uf
/dev/rmt/0 files_to_dump.
To make a full dump of a root file system
on c0t3d0, on a 150-MByte cartridge tape unit 0, use:
example# ufsdump
0cfu /dev/rmt/0 /dev/rdsk/c0t3d0s0
To make and verify an incremental dump
at level 5 of the usr partition of c0t3d0, on a 1/2" reel tape unit
1, use:
example# ufsdump 5fuv /dev/rmt/1 /dev/rdsk/c0t3d0s6
While
running, ufsdump emits many verbose messages. ufsdump returns the following
exit values:
- Normal exit.
- Startup errors encountered.
- Abort - no checkpoint
attempted.
- /dev/rmt/0
- default unit to dump to
- /etc/dumpdates
- dump
date record
- /etc/group
- to find group sys
- /etc/hosts
- to gain access to remote
system with drive
- /etc/vfstab
- list of file systems
cpio(1)
, tar(1)
,
dd(1M)
, devnm(1M)
, prtvtoc(1M)
, rmt(1M)
, shutdown(1M)
, ufsrestore(1M)
,
volcopy(1M)
, wall(1M)
, st(7D)
Fewer than 32 read errors
on the file system are ignored.
Because each reel requires
a new process, parent processes for reels that are already written hang
around until the entire tape is written.
ufsdump 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, ufsdump interacts with the operator on ufsdump’s control
terminal at times when ufsdump can no longer proceed, or if something is
grossly wrong. All questions ufsdump poses must be answered by typing yes
or no, as appropriate.
Since backing up a disk can involve a lot of time
and effort, ufsdump checkpoints at the start of each volume. If writing
that volume fails for some reason, ufsdump will, with operator permission,
restart itself from the checkpoint after a defective volume has been replaced.
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 should be performed
with the system running in single-user mode.
Incremental dumps allow for
convenient backup and recovery of active files on a more frequent basis,
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), 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
Although the Tuesday through 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.
ufsdump 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 ufsdump run slower instead of faster.
Most disks contain one or more overlapping slices because slice
2 covers the entire disk. The other slices are of various sizes and usually
do not overlap. For example, a common configuration places root on slice
0, swap on slice 1, /opt on slice 5 and /usr on slice 6.
It should be emphasized
that ufsdump dumps one ufs file system at a time. Given the above scenario
where slice 0 and slice 2 have the same starting offset, executing ufsdump
on slice 2 with the intent of dumping the entire disk would instead dump
only the root file system on slice 0. To dump the entire disk, the user
must dump the file systems on each slice separately.
The /etc/vfstab
file does not allow the desired frequency of backup for file systems to
be specified (as /etc/fstab did). Consequently, the w and W options assume
file systems should be backed up daily, which limits the usefulness of
these options.
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