03-26-2006
Most tape device drivers in UNIX support compression at the hardware level assuming the physical tape drive supports it. Compression is enabled or disabled by specifying the appropriate tape device. Tape density can also be specified in this manner. Refer to the st(7D) man pages for a detailed list of driver options.
For example:
tar cvf /dev/rmt/0hc directory-name # high density, hardware compression
or
tar cvf /dev/rmt/0h directory-name # high-density, no compression
Remember, hardware compression rarely increases overall capacity if the data stream is already compressed. That is, if all the files in the above example "directory-name" are already compressed, enabling hardware compression won't "double compress" and could easily increase the tape required due to duplicate overhead of the software and hardware compression algorithms.
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LEARN ABOUT OPENSOLARIS
tcopy
tcopy(1) User Commands tcopy(1)
NAME
tcopy - copy a magnetic tape
SYNOPSIS
tcopy source [destination]
DESCRIPTION
The tcopy utility copies the magnetic tape mounted on the tape drive specified by the source argument. The only assumption made about the
contents of a tape is that there are two tape marks at the end.
When only a source drive is specified, tcopy scans the tape, and displays information about the sizes of records and tape files. If a des-
tination is specified, tcopy makes a copies the source tape onto the destination tape, with blocking preserved. As it copies, tcopy pro-
duces the same output as it does when only scanning a tape.
The tcopy utility requires the use of Berkeley-compatible device names. For example,
example% tcopy /dev/rmt/1b /dev/rmt/2b
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWesu |
+-----------------------------+-----------------------------+
SEE ALSO
mt(1), ioctl(2), attributes(5)
NOTES
tcopy will only run on systems supporting an associated set of ioctl(2) requests.
SunOS 5.11 10 Mar 2000 tcopy(1)