wmtd(1M) DG/UX R4.11MU05 wmtd(1M)
NAME
wmtd - start the WORM magnetic tape device server
SYNOPSIS
/usr/sbin/wmtd wdevice=pdevice ...
where:
wdevice Device number in the /dev/wmt directory
pdevice Pathname of the physical device
DESCRIPTION
A WORM drive is a write-once read-many disk device. The WORM as
magnetic tape server (daemon), wmtd, is designed to make, as much as
possible, a WORM disk device act like a magnetic tape device. From
the user's perspective, all of the system tape archiving commands,
such as mt(1), dump2(1M), restore(1M), and sysadm(1M) will behave as
they do when archiving to magnetic tapes. An exception to this rule
is that a WORM disk may be written only once, a feature that makes
WORM drives a good choice for permanent archives.
A user opens a special file in the directory /dev/wmt. The DG/UX
kernel then communicates with the wmtd process to perform operations
on the WORM device. The wmtd process knows the physical device with
which to communicate by the logical-to-physical device mappings
specified on the command-line. For example, if the system
administrator wants /dev/wmt/0 and /dev/wmt/0n to be associated with
the device, /dev/rpdsk/2, then the mapping would be 0=/dev/rpdsk/2.
More than one device mapping may be specified when the system has
more than one WORM device, but only one device may be accessed at a
time.
The wmtd server automatically puts itself in the background and
detaches from any controlling terminal. Unanticipated errors are
communicated to the system through syslogd(1M). Only a user with
appropriate privilege can start the wmtd program. You must have
appropriate privilege to register and deregister physical disks. For
systems supporting the DG/UX Capability Option, appropriate privilege
is defined as having one or more specific capabilities enabled in the
effective capability set of the user. See the capdefaults(5) man
page for the default capabilities for this command.
On generic DG/UX systems, appropriate privilege means that your
process has an effective UID of root. See the
appropriateprivilege(5) man page for more information.
The preferred way to start the server is to let the system start it
at boot time. To have the system start wmtd, the system
administrator must modify the /etc/dgux.params initialization file.
The variable wmtdSTART should be set to "true" and the wmtdARG
should contain the command line arguments.
The protocol used between wmt(7) and wmtd is the same protocol used
by pmtd(1M).
FILES
/usr/include/sys/errno.h File describing DG/UX errno values.
SEE ALSO
pmtd(1M), mt(1), dump2(1M), restore(1M), sysadm(1M), cpio(1),
kill(2), ioctl(2), wmt(7), syslogd(1M), capdefaults(5).
CAVEATS
The ioctl(2) operations (with the command MTIOCTOP) supported by the
wmtd server are as follows: MTFSF, MTBSF, MTREW, MTOFFL, MTWEOF, and
MTNOP.
If a /dev/wmt device is specified as the input-output device using
one of the archiving commands and no valid mapping exists, wmtd
returns ENODEV (in errno) to the calling process.
The user with appropriate privilege should never send a SIGKILL (i.e.
kill -9) signal to wmtd. A SIGTERM (i.e. kill with no options)
signal will allow the server to "clean up" any read or write that may
be in progress. If the server is sent a SIGKILL signal when writing,
the remainder of the WORM cartridge will most likely be unusable.
When using cpio(1), the user with appropriate privilege should
specify the -B switch, as the wmtd server is slow when using small
buffers. For maximum efficiency, the buffer size should be a
multiple of the WORM device's sector size.
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