dump(8)

Name

dump − create file system dump

Syntax

/etc/dump [ key [ argument... ] filesystem ]

Description

The dump command copies all files changed after a certain date from a specified filesystem to a file, a pipe, magnetic tapes, or disks. The key specifies the date and other options to be used by dump.

Dumping a filesystem requires operator attention. An operator must intervene when the end of a tape or disk is reached, when the end of the dump occurs, or when an unrecoverable input disk read error occurs (if more than 32 read errors occur). In addition to alerting all operators in the operator group, dump interacts with the operator at the control terminal when dump can no longer proceed, or if something is grossly wrong. All questions that dump poses must be answered by typing yes or no.

Because a full dump uses considerable system time, dump checkpoints itself at the start of each tape or disk volume. If writing that volume fails, dump asks the operator to restart from the checkpoint after the present tape or disk has been replaced.

The dump utility reports to the operator periodically, giving usually low estimates of the number of blocks to write, the number of tapes or disks the dump will take, the time to completion, and the time until the tape or disk must be changed. The output is verbose, so that others know that the terminal controlling dump is busy, and will be for some time.

This utility supports EOT handling which allows the use of multiple media. The utility prompts for the next volume when it encounters the end of the current volume.

This utility supports the TA90 style sequential stacker loader device. The device ejects a cartridge wehn it is taken off line. The utility performs the device ejection on behalf of the user when it encounters a multivolume boundary during write or read operations involving tape. The device then automatically loads the next available tape (if there is one). The utility then attempts to access this next tape for a reasonable amount of time (approximately three minutes) before prompting the user for a manual reload operation.

Options

With the dump command, you specify a string of one or more of the options described below. If no options are specified, the key 9u is assumed.

0−9 Specifies the dump level. All files that were modified since the last date stored in the file /etc/dumpdates for the same filesystem at lesser levels will be dumped. If no date is determined by the level, the beginning of time is assumed. Thus, the level 0 causes the entire filesystem to be dumped.

B Indicates that the next argument is a number that specifies the size, in 1024-byte blocks, of a storage medium, such as a diskette or removable disk cartridge. See the first example. Additionally, permits the utility to kill subprocesses that have finished writing. (This provides some relief to small memory systems.)

b Indicates that the next argument is the blocking factor for tape records. The default is 10 and the maximum is 63. The tape records are stored in 1024-byte blocks.

d Indicates that the density of the tape, expressed in bits per inch, is taken from the next argument. This density is used in calculating the amount of tape used per reel. The default density is 1600 bpi.

f Places the dump on the file or device specified by the next argument. If the name of the file is −, dump writes to standard output. The default dump device is /dev/rmt0h.

Permits the program to treat the tape drive as a sequential loader device even though it is not represented as such in the system driver tables.

n Notifies, by means similar to a wall() command, all users in the group operator when dump needs operator attention.

S Prints output file size in bytes, or number of volumes for devices. See the third example.

s Indicates that the next argument specifies the size of the dump tape, in feet. When the specified size is reached, dump waits for the reel to be changed. The default tape size is 2300 feet.

u Writes the date of the beginning of the dump on the file /etc/dumpdates if the dump completes successfully. This file records a separate date for each filesystem and each dump level. The format of /etc/dumpdates consists of one free format record per line: filesystem name, increment level and ctime() format dump date. The superuser can carefully edit /etc/dumpdates to change any of the fields.

W Tells the operator which file systems need to be dumped. This information is taken from the files /etc/dumpdates and /etc/fstab. The W option causes dump 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 used, all other options are ignored, and dump exits immediately.

w Lists only those filesystems that need to be dumped.

Examples

This example dumps the filesystem /dev/ra0a to RX50 diskettes. The B option is needed when running restore() to read this dump.

dump 9Bf 400 /dev/rra2a /dev/ra0a

This example dumps the filesystem /usr/users to a 6250 bpi tape on a TU78 tape drive:

dump 0undf 6250 /dev/rmt?h /usr/users

This example reports number of bytes to be output for a level 0 dump of the root file system. Please note: the file test is not created.

dump 0Sf test /

Restrictions

The dump program aborts with a segmentation fault if your /etc/fstab file has been mis-formatted.

Estimated sizes for unuspported tape drives are based on 1600-bpi blocked tape.

Anything fewer than 32 read errors on the filesystem are ignored.

Each reel requires a new process, so child processes for reels already written remain until the entire tape is written (unless the −B option is specified).

Using a blocking factor other than the default may lead to higher performance. However, you must select a value that is compatible with the hardware limitations of the source and destination machines.

Files

/dev/rrp1g Default filesystem to dump from

/dev/rmt0h Default tape unit to dump to

/etc/dumpdates
Dump date record

/etc/fstab Dump table: file systems and frequency

/etc/group Operator group definition

/dev/tty Required for user interface

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