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vxdump - incremental file system dump


vxdump [ -cnotuwW ] [ -number ] [ -b blocking_factor ] [ -B records ]
[ -d density ] [ -f filename ] [ -s size ] [ -t tracks ]
[ -T time ] filenames




vxdump copies to magnetic tape all files specified in filenames in a VxFS file system that changed after a particular date.

On most devices, vxdump detects end-of-media and prompts you to change the media if there is insufficient space, so it is not necessary to specify the size of the device. However, if the dump requires multiple tapes and the tapes are to be read using an older version of vxrestore, or if the tape device handles end-of-media in a way that vxdump does not recognize, then you must specify the size of the device using the -B option or combining the -d and -s options.


Perform dumps with the file system unmounted or the system in single-user environment (see the init(8) manual page) to ensure a consistent dump. With snapshot capabilities enabled, the dump can be performed in the multi-user environment using a snapshot file system with the online backup facility: the snapof= filesystem option of the VxFS-specific mount command.

Up to 32 read errors on the file system are ignored.

Each reel requires a new process; parent processes for reels already written remain until the entire tape is written.

Neither vxdump nor vxrestore work with Storage Checkpoints.

Cluster File System Issues

No cluster issues; command operates the same on cluster file systems.


If no options are specified, vxdump assumes -9u, and dumps a default file system to the default device.

- number

number is a single digit in the range [0-9] and indicates the dump level. All files modified since the last date stored in the file /etc/dumpdates for the same file system at a lesser dump level are dumped. So the option -0 dumps the entire file system. If the specified level does not determine a date, the beginning of (UNIX) time is assumed.

-b " blocking_factor"

The vxdump command writes in units of logical record size times blocking_factor. The logical record size is 1024 bytes. The vxdump command uses a blocking factor of 10 for tapes with densities less than 6250 BPI, 32 for tapes with densities of 6250 BPI or greater, and 63 for cartridge tapes by default. This can be overridden by the -b option. The vxrestore command dynamically determines the blocking factor up to the default maximum of 63.

-B " records"

The number of logical records per volume. The vxdump logical record size is 1024 bytes. records can also be specified with a suffix to indicate a unit of measure other than 1024 bytes. You can append a k, m, g, or t to the number to indicate that the value is in kilobytes, megabytes, gigabytes, or terabytes, respectively. This option overrides the calculation of tape size based on length and density.


Cartridge. Specifies using a cartridge instead of the standard half-inch reel. This sets the density to 1000 BPI and the blocking factor to 63. The length is set to 425 feet. -c is incompatible with the -d option, unless you specify a density of 1000 BPI with that option.

-d " density"

The density of the tape (expressed in BPI) used to calculate the amount of tape used per tape reel. If -s is specified, a default density value of 1600 is assumed for a reel tape.

-f " filename"

Places the dump in the file filename instead of the tape. If the name of the file is - (dash), vxdump writes to the standard output. This option can be of the form machine : device to specify a tape device on a remote machine.


Whenever vxdump requires operator attention, notifies all users in group operator in similar fashion to that described in the wall(1) manual page.


Specifies /etc/vxdumpdates as the dump record file instead of the VxFS default file /etc/dumpdates.

-s " size"

The size of the dump tape in feet. When the specified size is reached, vxdump waits for reels to be changed. If -d is specified, a default size value of 2300 is assumed for a reel tape.

-T " date"

Uses the specified date as the starting time for the dump instead of the time determined by the /etc/dumpdates file. The format of date is the same as that described in the ctime(3) manual page. -T is useful for automated dump scripts to perform dumps over a specific period of time.

If the dump completes successfully, -u writes the date when the dump started to the file /etc/dumpdates. This file records a separate date for each file system and each dump level. The format of /etc/dumpdates is user-readable and consists of one free format record per line: file system name, increment level and dump date in ctime format. The file /etc/dumpdates can be edited to change any of the fields if necessary. The -u option is ignored for partial dumps.


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


For each file system in /etc/dumpdates, prints the most recent dump date and level, indicating which file systems should be dumped. If the -W option is specified, all other options are ignored and vxdump exits immediately.


vxdump requires operator intervention for any of the following conditions:

In addition to alerting all operators implied by the -n option, vxdump interacts with the control terminal operator by posing questions requiring yes or no answers when it cannot proceed or if there is a serious problem.

Because making a full dump typically requires considerable time, vxdump establishes a checkpoint at the start of each tape volume. If for any reason writing that volume fails, vxdump, with operator permission, restarts from the checkpoint after the old tape is rewound and removed and a new tape is mounted.

vxdump periodically reports information to the operator, including estimates (typically low) of the number of blocks to write, the number of tapes it requires, time required to complete, and the time remaining until tape change. The output is verbose to inform other users that the terminal controlling vxdump is busy and will be for a long period of time.


In most cases, the dump tape format is independent of the VxFS disk layout. A dump of a file system may even be restored on a file system of another file system type. There are some exceptions:

If you use vxdump to produce a dump intended for an earlier version of vxrestore, and if the dump requires multiple tapes, use the -s, -d, or -B option.

Dumps produced by older versions of vxdump can be read by the current version of vxrestore.


In the following example, assume that the file system is mounted at /mnt.

In this example, the entire file system ( /mnt ) is dumped on /dev/st1 and the size of the tape is two gigabytes.

vxdump -0 -B 2g -f /dev/st1 /mnt

Specifying the tape size in logical records:

vxdump 0Bf 2097152 /dev/st1 /mnt

The option argument 2097152 goes with the option letter B as it is the first option letter that requires an option argument. The option argument /dev/st1 goes with the option f as it is the second option letter that requires an option argument.


vxdump is based on the dump program from the 4.4 Berkeley Software Distribution, developed by the University of California, Berkeley, and its contributors.



Default tape drive.


New format-dump-date record. This is the default file for VxFS.


Alternate format-dump-date record. Can be substituted for /etc/dumpdates by using the -o option.


Contains static information about file systems.


Table of mounted file systems.


List of group operators.


setext(1), wall(1), mount_vxfs(1M), vxrestore(1M), close(2), open(2), ctime(3), getopt(3), fstab(5), init(8), mount(8)