MAN page from RedHat Other dump-0.3-9.i386.rpm

DUMP

Section: Maintenance Commands (8)
Index
BSD mandoc
BSD 4

NAME

dump - filesystem backup

SYNOPSIS

dump[0123456789BbhfusTdWnFP [argument ...]]filesystem
dump[0123456789BbhfusTdWnFP [argument ...]]directory

DESCRIPTION

Dumpexamines fileson a filesystemand determines which filesneed to be backed up. These filesare copied to the given disk, tape or otherstorage medium for safe keeping (see thef, PorFoptions below for doing remote backups).A dump that is larger than the output medium is broken intomultiple volumes.On most media the size is determined by writing until anend-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/orblock count options below.By default, the same output file name is used for each volumeafter prompting the operator to change media.

The following options are supported bydump:

0-9

Dump levels.A level 0, full backup,guarantees the entire file system is copied(but see also thehoption below).A level number above 0,incremental backup,tells dump tocopy all files new or modified since thelast dump of lower level. The defaultlevel is 9.

B records

The number of dump records per volume (this is interpreted as the sizein kilobytes).This option overrides the calculation of tape sizebased on length and density.

b blocksize

The number of kilobytes per dump record.

h level

Honor the user``nodump''flagDp Dv UF_NODUMPonly for dumps at or above the givenlevel The default honor level is 1,so that incremental backups omit such filesbut full backups retain them.

f file

Write the backup tofile filemay be a special device filelike/dev/rmt12(a tape drive),/dev/rsd1c(a disk drive),an ordinary file,or`-'(thestandard 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 promptingfor media changes.If the name of the file is of the form``host:file'' or``userAATThost:file'' dumpwrites to the named file on the remote host usingrmt(8).

P path

Makes a remote backup viapathprogram (usuallyrsh(1))instead ofrcmd(3).Backup is then done via the following command:

path -luser host/etc/rmt

Theuserandhostis taken from thefoption (see above).For example, you can do backup viassh(1)using the following command:

dump 0uPf ssh mynameAATTremotehost:/dev/tape /

See also theFoption.

F commandline

Same as thePoption above, but the full commandline for the program is given.For example if thermt(8)program does not reside in/etc/rmt you can do this:

dump 0uFf "ssh -l myname remotehost /usr/sbin/rmt" /dev/tape /

d density

Set tape density todensity The default is 1600BPI.

n

Wheneverdumprequires operator attention,notify all operators in the group``operator''by means similar to awall(1).

s feet

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

u

Update the file/etc/dumpdatesafter a successful dump.The format of/etc/dumpdatesis readable by people, consisting of onefree format record per line:filesystem name,increment levelandctime(3)format dump date. There may be only one entry per filesystem at each level.The file/etc/dumpdatesmay be edited to change any of the fields,if necessary.

T date

Use the specified date as the starting time for the dumpinstead of the time determined from looking in/etc/dumpdates The format of date is the same as that ofctime(3).This option is useful for automated dump scripts that wish todump over a specific period of time.TheToption is mutually exclusive from theuoption.

W

Dumptells the operator what file systems need to be dumped.This information is gleaned from the files/etc/dumpdatesand/etc/fstab TheWoption causesdumpto print out, for each file system in/etc/dumpdatesthe most recent dump date and level,and highlights those file systems that should be dumped.If theWoption is set, all other options are ignored, anddumpexits immediately.

w

Is like W, but prints only those filesystems which need to be dumped.

Dumprequires operator intervention on these conditions:end of tape,end of dump,tape write error,tape open error ordisk read error (if there are more than a threshold of 32).In addition to alerting all operators implied by thenkey,dumpinteracts with the operator ondump'scontrol terminal at times whendumpcan no longer proceed,or if something is grossly wrong.All questionsdumpposesmustbe answered by typing``yes''or``no'' appropriately.

Since making a dump involves a lot of time and effort for full dumps,dumpcheckpoints itself at the start of each tape volume.If writing that volume fails for some reason,dumpwill,with operator permission,restart itself from the checkpointafter the old tape has been rewound and removed,and a new tape has been mounted.

Dumptells 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, andthe time to the tape change.The output is verbose,so that others know that the terminalcontrollingdumpis busy,and will be for some time.

In the event of a catastrophic disk event, the time requiredto restore all the necessary backup tapes or files to diskcan be kept to a minimum by staggering the incremental dumps.An efficient method of staggering incremental dumpsto minimize the number of tapes follows:

Always start with a level 0 backup, for example:
```
/sbin/dump 0uf /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.
After a level 0, dumps of active filesystems 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 number of tapesfor each day, used on a weekly basis.Each week, a level 1 dump is taken, andthe daily Hanoi sequence repeats beginning with 3.For weekly dumps, another fixed set of tapes per dumped file system isused, also on a cyclical basis.

After several months or so, the daily and weekly tapes should getrotated 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 groupoperator

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 forreels already written just hang around until the entire tapeis written.

Dumpwith theWorwoptions does not report filesystems that have never been recordedin/etc/dumpdates even if listed in/etc/fstab

It would be nice ifdumpknew about the dump sequence,kept track of the tapes scribbled on,told the operator which tape to mount when,and provided more assistancefor the operator runningrestore.

The Linux port ofdumpis not able yet to produce correct multi-volume backups.

HISTORY

Adumpcommand appeared in Version 6 AT&T UNIX.

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