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DUMP(8) BSD System Manager's Manual DUMP(8)

NAME

dduummpp - filesystem backup

SYNOPSIS

dduummpp [-00112233445566778899ccnnuu] [-BB records] [-bb blocksize] [-dd density] [-ff file]

[-hh level] [-ss feet] [-TT date] filesystem

dduummpp [-WW | -ww]

(The 4.3BSD option syntax is implemented for backward compatibility, but is not documented here.)

DESCRIPTION

DDuummpp examines files on a filesystem and determines which files need to be

backed up. These files are copied to the given disk, tape or other stor-

age medium for safe keeping (see the -ff 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. 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. The following options are supported by dduummpp:

-00-99 Dump levels. A level 0, full backup, guarantees the entire file

system is copied (but see also the -hh option below). A level

number above 0, incremental backup, tells dump to copy all files

new or modified since the last dump of the same or lower level.

The default level is 9.

-BB records

The number of dump records per volume. This option overrides the

calculation of tape size based on length and density.

-bb blocksize

The number of kilobytes per dump record.

-cc Modify the calculation of the default density and tape size to be

more appropriate for cartridge tapes.

-dd density

Set tape density to density. The default is 1600BPI.

-ff file

Write the backup to file; file may be a special device file like

/dev/rmt12 (a tape drive), /dev/rdisk1s3 (a disk drive), an ordi-

nary file, or `-' (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'', dduummpp writes to the named file on the remote host using rmt(8).

-hh level

Honor the user ``nodump'' flag 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.

-nn Whenever dduummpp requires operator attention, notify all operators

in the group ``operator'' by means similar to a wall(1).

-ss feet

Attempt to calculate the amount of tape needed at a particular density. If this amount is exceeded, dduummpp prompts for a new tape. It is recommended to be a bit conservative on this option. The default tape length is 2300 feet.

-TT date

Use the specified date as the starting time for the dump instead

of the time determined from looking in /etc/dumpdates. The for-

mat of date is the same as that of ctime(3). This option is use-

ful for automated dump scripts that wish to dump over a specific

period of time. The -TT option is mutually exclusive from the -uu

option.

-uu Update the file /etc/dumpdates after a successful dump. The for-

mat of /etc/dumpdates is readable by people, consisting of one

free format record per line: filesystem name, increment level and

ctime(3) format dump date. There may be only one entry per

filesystem at each level. The file /etc/dumpdates may be edited

to change any of the fields, if necessary.

-WW DDuummpp tells the operator what file systems need to be dumped.

This information is gleaned from the files /etc/dumpdates and

/etc/fstab. The -WW option causes dduummpp 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 -WW option is set, all other options are ignored, and dduummpp

exits immediately.

-ww Is like W, but prints only those filesystems which need to be

dumped.

DDuummpp 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 -nn key, dduummpp interacts with the operator on dump's control

terminal at times when dduummpp can no longer proceed, or if something is grossly wrong. All questions dduummpp poses must be answered by typing ``yes'' or ``no'', appropriately.

Since making a dump involves a lot of time and effort for full dumps,

dduummpp checkpoints itself at the start of each tape volume. If writing that volume fails for some reason, dduummpp 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. DDuummpp 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 dduummpp 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:

++oo Always start with a level 0 backup, for example:

/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.

++oo After a level 0, dumps of active file systems are taken on a

daily basis, using a modified Tower of Hanoi algorithm, with

this sequence of dump levels:

3 2 5 4 7 6 9 8 9 9 ...

For the daily dumps, it should be possible to use a fixed num-

ber 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.

FILES

/dev/rmt8 default tape unit to dump to

/etc/dumpdates dump date records

/etc/fstab dump table: file systems and frequency

/etc/group to find group operator

restore(8), rmt(8), dump(5), fstab(5)

DIAGNOSTICS Many, and verbose. Dump 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.

BUGS

Fewer than 32 read errors on the filesystem are ignored. Each reel requires a new process, so parent processes for reels already written just hang around until the entire tape is written.

DDuummpp with the -WW or -ww options does not report filesystems that have

never been recorded in /etc/dumpdates, even if listed in /etc/fstab.

It would be nice if dduummpp knew about the dump sequence, kept track of the

tapes scribbled on, told the operator which tape to mount when, and pro-

vided more assistance for the operator running restore. HISTORY A dduummpp command appeared in Version 6 AT&T UNIX. 4th Berkeley Distribution May 1, 1995 4th Berkeley Distribution