DUMP_LFS(8) | System Manager's Manual | DUMP_LFS(8) |
dump_lfs
, rdump_lfs
—
dump_lfs |
[-0123456789aceFnStuX ]
[-B records]
[-b blocksize]
[-d density]
[-f file]
[-h level]
[-k read-blocksize]
[-L label]
[-l timeout]
[-r cachesize]
[-s feet]
[-T date]
[-U dumpdev]
[-x snap-backup]
files-to-dump |
dump_lfs |
[-W |
-w ]
(The 4.3BSD option syntax is implemented for backward compatibility, but is not documented here). |
dump_lfs
examines files on a file system and determines
which files need to be backed up. These files are copied to the given disk,
tape or other storage medium for safe keeping (see the
-f
option below for doing remote backups). A dump that
is larger than the output medium is broken into multiple volumes. On most
media the size is determined by writing until an end-of-media indication is
returned. This can be enforced by using the -a
option.
On media that cannot reliably return an end-of-media indication (such as some cartridge tape drives) each volume is of a fixed size; the actual size is determined by the tape size and density and/or block count options below. By default, the same output file name is used for each volume after prompting the operator to change media.
files-to-dump is either a single file
system, or a list of files and directories on a single file system to be
backed up as a subset of the file system. In the former case,
files-to-dump may be the device of a file system, the
path to a currently mounted file system, the path to an unmounted file
system listed in /etc/fstab, or, if
-F
is given, a file system image. In the latter
case, certain restrictions are placed on the backup:
-u
is ignored, the only dump level that is supported
is -0
, and all of the files must reside on the same
file system.
The following options are supported by
dump_lfs
:
-0-9
-h
option below). A level
number above 0, incremental backup, tells dump to copy all files new or
modified since the last dump of a lower level. The default level is
9.-a
-B
records-b
blocksize-c
-d
density-e
-F
-f
file-
’ (the
standard output). Multiple file names may be given as a single argument
separated by commas. Each file will be used for one dump volume in the
order listed; if the dump requires more volumes than the number of names
given, the last file name will used for all remaining volumes after
prompting for media changes. If the name of the file is of the form
“host:file”, or “user@host:file”,
dump_lfs
writes to the named file on the remote
host using rmt(8). Note that
methods more secure than rsh(1)
(such as ssh(1)) can be used to
invoke rmt(8) on the remote
host, via the environment variable RCMD_CMD
. See
rcmd(3) for more details.-h
levelUF_NODUMP
) only for dumps at or above the given
level. The default honor level is 1, so that
incremental backups omit such files but full backups retain them.-k
read-blocksize-l
timeoutdump_lfs
falls
back to the default behavior, and prompts the operator for the next
tape.-L
labelLBLSIZE
(currently 16) characters, which must include the terminating
‘\0
’.-n
dump_lfs
requires operator attention,
notify all operators in the group “operator” using
wall(1).-r
cachesize-k
option for the size of the
buffers. Maximum is 512, the size of the cache is limited to 15% of the
avail RAM by default.-s
feetdump_lfs
prompts for a
new tape. It is recommended to be a bit conservative on this option. The
default tape length is 2300 feet.-S
-t
dump_lfs
will have the time prepended to them. Also, the completion time interval
estimations will have the estimated time at which the dump will complete
printed at the end of the line.-T
date-T
option is mutually exclusive from
the -u
option.-u
-T
option is used or if a list of files or subdirectories is being dumped (as
opposed to an entire file system), then -u
is
ignored.-U
dumpdev-u
but specifies the device in
/etc/dumpdates as dumpdev.
This option can be used with subdir dumps and with the
-T
option.-X
-x
flag is provided for compatibility
with dump(8); it functions
exactly as the -X
flag does (its argument is
ignored).-W
dump_lfs
tells the operator what file systems need
to be dumped. This information is gleaned from the files
/etc/dumpdates and
/etc/fstab. The -W
option
causes dump_lfs
to print out, for each file system
in /etc/dumpdates the most recent dump date and
level, and highlights those file systems that should be dumped. If the
-W
option is set, all other options are ignored,
and dump_lfs
exits immediately.-w
If dump_lfs
honors the
“nodump” flag (UF_NODUMP
), files with
the “nodump” flag will not be backed up. If a directory has
the “nodump” flag, this directory and any file or directory
under it will not be backed up.
dump_lfs
requires operator intervention on
these conditions: end of tape, end of dump, tape write error, tape 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, dump_lfs
interacts with the operator on
dump_lfs
's control terminal at times when
dump_lfs
can no longer proceed, or if something is
grossly wrong. All questions dump_lfs
poses
must be answered by typing “yes” or
“no”, appropriately.
Since making a dump involves a lot of time and effort for full
dumps, dump_lfs
checkpoints itself at the start of
each tape volume. If writing that volume fails for some reason,
dump_lfs
will, with operator permission, restart
itself from the checkpoint after the old tape has been rewound and removed,
and a new tape has been mounted.
dump_lfs
tells the operator what is going
on at periodic intervals, including usually low estimates of the number of
blocks to write, the number of tapes it will take, the time to completion,
and the time to the tape change. The output is verbose, so that others know
that the terminal controlling dump_lfs
is busy, and
will be for some time.
In the event of a catastrophic disk event, the time required to restore all the necessary backup tapes or files to disk can be kept to a minimum by staggering the incremental dumps. An efficient method of staggering incremental dumps to minimize the number of tapes follows:
/sbin/dump -0u -f /dev/nrst1 /usr/src
This should be done at set intervals, say once a month or once every two months, and on a set of fresh tapes that is saved forever.
3 2 5 4 7 6 9 8 9 9 ...
For the daily dumps, it should be possible to use a fixed number of tapes for each day, used on a weekly basis. Each week, a level 1 dump is taken, and the daily Hanoi sequence repeats beginning with 3. For weekly dumps, another fixed set of tapes per dumped file system is used, also on a cyclical basis.
After several months or so, the daily and weekly tapes should get rotated out of the dump cycle and fresh tapes brought in.
If dump_lfs
receives a
SIGINFO
signal (see the “status”
argument of stty(1)) whilst a
backup is in progress, statistics on the amount completed, current transfer
rate, and estimated finished time, will be written to the standard error
output.
dump_lfs
.
TAPE
dump_lfs
will use
the device specified via TAPE
as the dump device.
TAPE
may be of the form “tapename”,
“host:tapename”, or “user@host:tapename”.RCMD_CMD
dump_lfs
will use RCMD_CMD
rather than rsh(1) to invoke
rmt(8) on the remote
machine.TIMEFORMAT
-t
option. TIMEFORMAT
is a
string containing embedded formatting commands for
strftime(3). The total
formatted string is limited to about 80 characters, if this limit is
exceeded then “ERROR: TIMEFORMAT too long, reverting to
default” will be printed and the time format will revert to the
default one. If TIMEFORMAT
is not set then the
format string defaults to “%T %Z”_PATH_DEFTAPE
in /usr/include/paths.h.dump_lfs
exits with zero status on
success. Startup errors are indicated with an exit code of 1; abnormal
termination is indicated with an exit code of 3.
dump_lfs
command appeared in NetBSD
1.5.
Each reel requires a new process, so parent processes for reels already written just hang around until the entire tape is written.
dump_lfs
with the
-W
or -w
options does not
report file systems that have never been recorded in
/etc/dumpdates, even if listed in
/etc/fstab.
When dumping a list of files or subdirectories, access privileges are required to scan the directory (as this is done via the fts(3) routines rather than directly accessing the file system).
It would be nice if dump_lfs
knew about
the dump sequence, kept track of the tapes scribbled on, told the operator
which tape to mount when, and provided more assistance for the operator
running restore(8).
March 25, 2019 | NetBSD 9.4 |