UFSDUMP(8) Maintenance Procedures UFSDUMP(8)


ufsdump - incremental file system dump


/usr/sbin/ufsdump [options] [arguments] files_to_dump


ufsdump backs up all files specified by files_to_dump (usually either a
whole file system or files within a file system changed after a certain
date) to magnetic tape, diskette, or disk file.

The ufsdump command can only be used on unmounted file systems, or those
mounted read-only. Attempting to dump a mounted, read-write file system
might result in a system disruption or the inability to restore files
from the dump. Consider using the fssnap(8) command to create a file
system snapshot if you need a point-in-time image of a file system that
is mounted.

If a filesystem was mounted with the logging option, it is strongly
recommended that you run ufsdump as the root user. Running the command as
a non-root user might result in the creation of an inconsistent dump.

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:


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(8) 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).


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 inch tape

6250 BPI

1/4 inch cartridge

1000 BPI The tape densities and other options are documented in
the st(4D) man page.


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(8). 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


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.

L string

Sets the tape label to string, instead of the default none. string
may be no more than sixteen characters long. If it is longer, it is
truncated and a warning printed; the dump will still be done. The
tape label is specific to the ufsdump tape format, and bears no
resemblance to IBM or ANSI-standard tape labels.


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(8) command. Otherwise, such messages are sent only
to the terminals (such as the console) on which the user running
ufsdump is logged in.

N device_name

Use device_name when recording information in /etc/dumpdates (see the
u option) and when comparing against information in /etc/dumpdates
for incremental dumps. The device_name provided can contain no white
space as defined in scanf(3C) and is case-sensitive.


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 inch tape

2300 feet

60-Mbyte 1/4 inch cartridge

425 feet

150-Mbyte 1/4 inch cartridge

700 feet


1422 blocks (Corresponds to a 1.44-Mbyte diskette, with one
cylinder reserved for bad block information.)


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 inch cartridge

9 tracks

150-Mbyte 1/4 inch cartridge

18 tracks

T time_wait[hms]

Sets the amount of time to wait for an autoload command to complete.
This option is ignored unless the l option has also been specified.
The default time period to wait is two minutes. Specify time units
with a trailing h ( for hours), m (for minutes), or s (for seconds).
The default unit is minutes.


Update the dump record. Add an entry to the file /etc/dumpdates, for
each file system successfully dumped that includes the file system
name (or device_name as specified with the N option), date, and dump


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.


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.


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:


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 named directories
that may be examined by the user running ufsdump, as well as any
explicitly-named files, are dumped. This dump is equivalent to a
level 0 dump of the indicated portions of the filesystem, except that
/etc/dumpdates is not updated even if the -u option has been
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.


See largefile(7) for the description of the behavior of ufsdump when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).


Example 1: Using ufsdump

The following command makes a full dump of a root file system on c0t3d0,
on a 150-MByte cartridge tape unit 0:

example# ufsdump 0cfu /dev/rmt/0 /dev/rdsk/c0t3d0s0

The following command makes and verifies an incremental dump at level 5
of the usr partition of c0t3d0, on a 1/2 inch reel tape unit 1,:

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.



default unit to dump to


dump date record


to find group sys


to gain access to remote system with drive


list of file systems


cpio(1), tar(1), scanf(3C), st(4D), ufsdump(5), attributes(7),
largefile(7), dd(8), devnm(8), fssnap(8), prtvtoc(8), rmt(8),
shutdown(8), ufsrestore(8), volcopy(8), wall(8)


Read Errors

Fewer than 32 read errors on the file system are ignored.

Process Per Reel

Because each reel requires a new process, parent processes for reels that
are already written hang around until the entire tape is written.

Operator Intervention

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.

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 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.

Process Priority of ufsdump

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.

Overlapping Partitions

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


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.

April 9, 2016 UFSDUMP(8)