UFSDUMP(8) Maintenance Commands and Procedures UFSDUMP(8)

NAME

ufsdump - incremental file system dump

SYNOPSIS

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

DESCRIPTION

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.

OPTIONS

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(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).


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 inch tape

6250 BPI


1/4 inch cartridge

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


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.


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(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.


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 inch tape

2300 feet


60-Mbyte 1/4 inch cartridge

425 feet


150-Mbyte 1/4 inch 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 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.


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 (or device_name as specified with the N option),
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.

OPERANDS

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
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.

USAGE

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

EXAMPLES

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

EXIT STATUS

While running, ufsdump emits many verbose messages. ufsdump returns
the following exit values:

0

Normal exit.


1

Startup errors encountered.


3

Abort - no checkpoint attempted.

FILES

/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

SEE ALSO

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)

NOTES

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 separately.

BUGS

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)