NAME

dump, rdump − incremental file system dump

SYNOPSIS

/usr/etc/dump [ options [ arguments ] ] filesystem

DESCRIPTION

dump backs up all files in filesystem, or files changed after a certain date, to magnetic tape; on Sun386i, Sun-3/80 and SPARCstation 1 systems, dump works on both magnetic tape and diskettes.  options is a string that specifies dump options, as shown below.  Any arguments supplied for specific options are given as subsequent words on the command line, in the same order as that of the options listed. 

If no options are given, the default is 9u. 

OPTIONS

0−9 The “dump level.” All files in the filesystem that have been modified since the last dump at a lower dump level are copied to the volume.  For instance, if you did a “level 2” dump 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 filesystem to the dump volume. 

b factor
Blocking factor. Specify the blocking factor for tape writes. The default is 20 blocks per write. Note: the blocking factor is specified in terms of 512 bytes blocks, for compatibility with tar(1).  The default blocking factor for tapes of density 6250BPI and greater is 64.  The default blocking factor for cartridge tapes (c option specified) is 126.  The highest blocking factor available with most tape drives is 126. 

c Cartridge.  Use a cartridge instead of the standard half-inch reel.  This sets the density to 1000BPI, the blocking factor to 126, and the length to 425 feet.  This option also sets the “inter-record gap” to the appropriate length.  When cartridge tapes are used, and this option is not specified, dump 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.  The density of the tape, expressed in BPI, is taken from bpi.  This is used to keep a running tab on the amount of tape used per reel.  The default density is 1600 except for cartridge tape.  Unless a higher density is specified explicitly, dump uses its default density — even if the tape drive is capable of higher-density operation (for instance, 6250BPI).  Note: the density specified should correspond to the density of the tape device being used, or dump will not be able to handle end-of-tape properly.  The d option is not compatible with the D option. 

D Diskette. Specify diskette as the dump media. 

f dump-file
Dump file. Use dump-file as the file to dump to, instead of /dev/rmt8.  If dump-file is specified as ‘−’, dump to the standard output.  If the filename argument is of the form machine:device, dump to a remote machine. Since dump is normally run by root, the name of the local machine must appear in the .rhosts file of the remote machine.  If the filename argument is of the form user@machine:device, dump 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 root from the local machine.  If dump is called as rdump, the dump device defaults to dumphost:/dev/rmt8.  To direct the output to a desired remote machine, set up an alias for dumphost in the file /etc/hosts. 

n Notify.  When this option is specified, if dump requires attention, it sends a terminal message (similar to wall(1)) to all operators in the “operator” group. 

s size Specify the size of the volume being dumped to. When the specified size is reached, dump waits for you to change the volume.  dump interprets the specified size as the length in feet for tapes, and cartridges and as the number of 1024 byte blocks for diskettes.  The following are defaults:

tape 2300 feet

cartridge 425 feet

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

t tracks
Specify the number of tracks for a cartridge tape. On all Sun-2 systems the default is 4 tracks, although some Sun-2 systems have 9 track drives. On all other machines the default is 9 tracks. The t option is not compatible with the D option. 

u Update the dump record.  Add an entry to the file /etc/dumpdates, for each filesystem successfully dumped that includes the filesystem name, date, and dump level.  This file can be edited by the super-user. 

w List the filesystems that need backing up.  This information is gleaned from the files /etc/dumpdates and /etc/fstab.  When the w option is used, all other options are ignored.  After reporting, dump exits immediately. 

W Like w, but includes all filesystems that appear in /etc/dumpdates, along with information about their most recent dump dates and levels.  Filesystems that need backing up are highlighted. 

FILES

/dev/rmt8 default unit to dump to

dumphost:/dev/rmt8
default remote unit to dump to if called as rdump

/etc/dumpdates dump date record

/etc/fstab dump table: file systems and frequency

/etc/group to find group operator

/etc/hosts

SEE ALSO

tar(1), wall(1), dump(5), fstab(5), restore(8), shutdown(8)

DIAGNOSTICS

While running, dump emits many verbose messages. 

Exit Codes

0 Normal exit. 

1 Startup errors encountered. 

3 Abort − no checkpoint attempted. 

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. 

It is recommended that incremental dumps also be performed with the system running in single-user mode. 

dump does not support multi-file multi-volume tapes. 

NOTES

Operator Intervention

dump 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, dump interacts with the operator on dump’s control terminal at times when dump can no longer proceed, or if something is grossly wrong.  All questions dump poses must be answered by typing yes or no, as appropriate. 

Since backing up a disk can involve a lot of time and effort, dump checkpoints at the start of each volume.  If writing that volume fails for some reason, dump will, with operator permission, restart itself from the checkpoint after a defective volume has been replaced. 

dump reports periodically, and in  verbose fashion.  Each report includes estimates of the percentage of the dump completed and how long it will take to complete the dump. 

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 allow for convenient backup and recovery on a more frequent basis of active files, 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), it is a good idea to 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 MonTueWedThuFri
Week 1:Full55553
Week 2:55553
Week 3:55553
Week 4:55553

Although the Tuesday — 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 dump

dump 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 dump run slower instead of faster. 

Sun Release 4.0  —  Last change: 9 September 1987