medium changer control
chio utility is used to control the
operation of medium changers, such as those found in tape and optical disk
The options are as follows:
- Use the device changer rather than the default device /dev/ch0.
A medium changer apparatus is made up of elements. There are five element types: picker (medium transport), slot (storage), portal (import/export), drive (data transfer), and voltag (select by volume identifier). The voltag pseudo-element type allows the selection of tapes by their volume code, which is typically a barcode on the tape. In this command description, the shorthand ‘ET’ will be used to represent an element type, and ‘EU’ will be used to represent an element unit. For example, to represent the first robotic arm in the changer, the ET would be “picker” and the EU would be “0”.
The following commands are supported:
exchangesrc-ET src-EU dst1-ET dst1-EU [dst2-ET dst2-EU] [
- Performs a media unit exchange operation. The media unit in
src-ET/src-EU is moved to
dst1-ET/dst1-EU and the media
unit previously in
dst1-ET/dst1-EU is moved to
dst2-ET/dst2-EU. In the case
of a simple exchange,
dst2-ET/dst2-EU is omitted and
the values src-ET/src-EU are
used in their place. The optional modifiers
inv2specify whether the media units are to be inverted before insertion into dst1-ET/dst2-EU and dst2-ET/dst2-EU respectively.
Note that not all medium changers support the
exchangeoperation; the changer must have multiple free pickers or emulate multiple free pickers with transient storage.
- Report which picker unit the changer is currently configured to use.
movefrom-ET from-EU to-ET to-EU [
- Moves the media unit from
to-ET/to-EU. If the optional
invis specified, the media unit will be inverted before insertion. If from-ET is a drive,
chiowill first attempt to open and perform an
MTOFFLoperation on the st(4) device corresponding to from-EU. By default, the st(4) device /dev/rstX is used, where X is the from-EU. This mapping can be changed by using the chio.conf(5) file.
- Report the number of slots, drives, pickers, and portals in the changer, and which picker unit the changer is currently configured to use.
positionto-ET to-EU [
- Position the picker in front of the element described by
to-ET/to-EU. If the optional
invis specified, the media unit will be inverted before insertion.
Note that not all changers behave as expected in response to this command.
- Configure the changer to use picker unit.
-vVa] [ET] Report the status of all elements in the changer. If ET is specified, report the status of all elements of type ET.
- Print the primary volume tag for each loaded medium, if any. The volume tag is printed as “<LABEL:SERIAL>”.
- Print the alternate volume tag for each loaded medium, if any.
- Print all additional information (as in
The status bits output are defined as follows:
- Element contains a media unit.
- Media was deposited into element by an outside human operator.
- Element is in an abnormal state.
- Media in this element is accessible by a picker.
- Element supports passing media (exporting) to an outside human operator.
- Element supports receiving media (importing) from an outside human operator.
- The default changer may be overridden by setting this environmental variable to the desired changer device.
- Default changer device.
- Optional configuration file to set up a non-default mapping between st(4) devices and changer drives.
Move the media in slot 3 (fourth slot) to drive 0 (first drive):
# chio move slot 3 drive 0
Move the media with volume tag 000007L2 to drive 1 (second drive):
# chio move voltag 00007L2 drive 1
Configure the changer to use picker 2 (third picker) for operations:
# chio setpicker 2
mt(1), ch(4), st(4), chio.conf(5)
chio utility appeared in
chio program and SCSI changer driver
were written by Jason R. Thorpe for And