multibuf1

Usage

Overview

multibuf is a tape archive manager which provides the capability of extending a single logical archive over multiple physical media volumes.
multibuf is part of the KBackup package. See the documentation of KBackup for more information and the conditions of use.

Options

-r, --read

Set read mode. The archive is read from the device named in filename and written to stdout.

-w, --write (default)

Set write mode. The archive is read from stdin and written to the device named in filename.

-v, --verbose

Enable verbose progress reporting.

-m, --multibuf buffers

This enables real double-buffering using shared memory (Linux only) which can be used to keep a tape drive streaming continuously. The parameter is the number of shared buffers to use (at least 2).

-b, --blocksize byte_count (default = 1024)

This sets the minimal size of the data blocks used for the single write/read calls. Normally you should not change this.

-n, --nblocks block_count (default = 100, minimum = 5)

Use this option to change the size of the buffers used by multibuf.

-c, --command shell-command

Set command1, which is executed at end of medium. The default is "dialog --title with next volume? This command is expected to exit with a status of 0 to indicate that a retry should be performed.

-C, --command2 shell-command

Set command2, which is executed at beginning of medium. The default is "mt rewind </dev/tty >/dev/tty". The exit status of this command is not checked.

-R, --retry-command shell-command

Set command to execute when finding wrong sequence number. The default is "dialog --title "KBackup's MultiBuf" --yesno "Detected wrong sequence number. Retry?" 6 50 </dev/tty >/dev/tty". This command is expected to exit with a status of 0 to indicate that a retry should be performed.

-1, --end-only

Only execute command at end of media. This option disables command2 processing.

-2, --begin-and-end (default)

Exeute commands at end and begin of media. This option enables command2 processing.

-s, --settings

Display settings.

-x, --exit

Exit after processing options (for testing).

-h, --header

Add header/sequence information to data. This writes media headers with volume sequencing and block sizing information when writing an archive, or utilizes these headers when reading an archive.

-E, --no-endmarker

Do not use an endmarker. This disables archive writing of archive endmarkers when writing an an archive, and disables checking for these endmarkers when reading an archive.

-F, --file-endmarker

Write endmarker as a file on a mounted medium, or expect such an endmarker when reading from a mounted medium.

-D, --disable-filemark-fix

For debugging purpose only.

-V, --version

Print version information to stderr.

Exit status

0=success, 1=read error, 2=write error, 3=wrong sequence

Examples

You can use multibuf without KBackup. An example:
tar czvf - | multibuf -w -m 10 /dev/tape
This will write a tar file using double buffering and possibly spanning multiple physical volumes.