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HP-UX Reference > D


HP-UX 11i Version 3: February 2007

Technical documentation

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dump, rdump — incremental file system dump, local or across network


/usr/sbin/dump [option [argument ...] filesystem]

/usr/sbin/rdump [option [argument ...] filesystem]


The dump and rdump commands copy to magnetic tape all files in the filesystem that have been changed after a certain date. This information is derived from the files /var/adm/dumpdates and /etc/fstab. option specifies the date and other options about the dump. option consists of characters from the set 0123456789bdfnsuWw. The dump and rdump commands work only on file systems of type hfs. If the given file system is not of type hfs, dump and rdump will abort after printing an error message.



This number is the "dump level". All files modified since the last date stored in file /var/adm/dumpdates for the same file system at lesser levels will be dumped. If no date is determined by the level, the beginning of time is assumed. Thus, the option 0 causes the entire file system to be dumped.


The blocking factor is taken from the next argument (default is 10 if not specified). Block size is defined as the logical record size times the blocking factor. dump writes logical records of 1024 bytes. When dumping to tapes with densities of 6250 BPI or greater without using the b option, the default blocking factor is 32.


The density of the tape (expressed in BPIs) is taken from the next argument. This is used in calculating the amount of tape used per reel. The default value of 1600 assumes a reel tape.


Place the dump on the next argument file instead of the tape. If the name of the file is -, dump writes to the standard output. When using rdump, this option should be specified, and the next argument supplied should be of the form machine:device.


Whenever dump and rdump require operator attention, notify all users in group operator by means similar to that described by wall(1).


The size of the dump tape is specified in feet. The number of feet is taken from the next argument. When the specified size is reached, dump and rdump wait for reels to be changed. The default tape size value of 2300 feet assumes a reel tape.


If the dump completes successfully, write on file /var/adm/dumpdates the date when the dump started. This file records a separate date for each file system and each dump level. The format of /var/adm/dumpdates is user-readable and consists of one free-format record per line: file system name, increment level, and dump date in ctime(3C) format. The file /var/adm/dumpdates can be edited to change any of the fields if necessary.


For each file system in /var/adm/dumpdates, print the most recent dump date and level, indicating which file systems should be dumped. If the W option is set, all other options are ignored and dump exits immediately.


Operates like W, but prints only file systems that need to be dumped.

If no arguments are given, option is assumed to be 9u and a default file system is dumped to the default tape.

Sizes are based on 1600-BPI blocked tape; the raw magnetic tape device must be used to approach these densities. Up to 32 read errors on the file system are ignored. Each reel requires a new process; thus parent processes for reels already written remain until the entire tape is written.

The rdump command creates a server, /usr/sbin/rmt or /etc/rmt, on the remote machine to access the tape device.

dump and rdump require operator intervention for any of the following conditions:

  • end of tape,

  • end of dump,

  • tape-write error,

  • tape-open error, or

  • disk-read error (if errors exceed threshold of 32).

In addition to alerting all operators implied by the n option, dump and rdump interact with the control terminal operator by posing questions requiring yes or no answers when it can no longer proceed or if something is grossly wrong.

Since making a full dump involves considerable time and effort, dump and rdump each establish a checkpoint at the start of each tape volume. If, for any reason, writing that volume fails, dump and rdump will, with operator permission, restart from the checkpoint after the old tape has been rewound and removed and a new tape has been mounted.

dump and rdump periodically report information to the operator, including typically low estimates of the number of blocks to write, the number of tapes it will require, the time needed for completion, and the time remaining until tape change. The output is verbose to inform other users that the terminal controlling dump and rdump is busy and will be for some time.

Access Control Lists (ACLs)

The optional entries of a file's access control list (ACL) are not backed up with dump and rdump. Instead, the file's permission bits are backed up and any information contained in its optional ACL entries is lost (see acl(5)).


In the following example, assume that the file system /mnt is to be attached to the file tree at the root directory, (/). This example causes the entire file system (/mnt) to be dumped on /dev/rmt/c0t0d0BEST and specifies that the density of the tape is 6250 BPI.

  • /usr/sbin/dump 0df 6250 /dev/rmt/c0t0d0BEST /mnt


dump will not backup a file system containing large files.

Tapes created from file systems containing files with UID/GIDs greater than 60,000 will have a new magic number in the header to prevent older versions of restore(1M) from incorrectly restoring ownerships for these files.


dump and rdump were developed by the University of California, Berkeley.



Default file system to dump from.


Default tape unit to dump to.


New format-dump-date record.


Dump table: file systems and frequency.


Used to find group operator.

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