Copyright Digital Equipment Corp. All rights reserved.
Description
The mrd_startup(3mrd) function can be used to obtain information
about a supported Medium-Changer. Because the startup time on
some robots (HSJ connected SCSI robots) can be relatively long,
this routine can also be used to hold open the robot while mrd_
show(3mrd) routines are used to collect information about the
different robot elements.
The mrd_shutdown(3mrd) routine should be used to close a robot
before other MRD routines are called. With the exception of
mrd_show(3mrd) the MRD common routines call mrd_startup(3mrd)
themselves and can't make use of robot_info_t filled in by mrd_
startup(3mrd).
Robot Information
The robot_info_t data structure is defined in the include file
<mrd_common.h>. The fields of this data structure are described
below:
o channel - This is the file descriptor, channel number or other
operating system specific handle assigned to the process for
the robot, when mrd_startup(3mrd) is successful. It should
not be used directly and should only be closed through mrd_
shutdown(3mrd). When mrd_show(3mrd) is provided a robot_info_t
where the channel is not BAD_CHANNEL, it will assume the robot
is open and try to use that handle.
o robot_name - This is set to the address of the robot_name
argument provided to mrd_startup(3mrd).
o robot_type - MRD attempts to identify a robot using the SCSI
inquiry data obtained during the startup. This is a value
to indicate the family or type of medium-changer. Recognized
types are:
DLT_ROBOT TZ857, TZ867, TZ875, TZ877, TZ885, TZ887
RDAT_ROBOT TLZ6L, TLZ7L, TLZ9L
TL820_ROBOT TL820, TL822, TL826
TL810_ROBOT TL810, TL812
TL800_ROBOT TL891
OVERLAND_ROBOT TKZ6x
RW5XX_ROBOT RW500
UNKNOWN_ROBOT A type not recognized
o arch_type - This indicates the I/O architecture used to
communicate with the medium-changer. OpenVMS supports SCSI
(ARCH_SCSI) and DSA (ARCH_DSA) connected medium-changers. HSJ
and HSD connected robots are considered SCSI robots. Digital
UNIX and Windows NT only support SCSI connected robots.
o vision_present - This flag indicates that the robot supports
a vision system that can be used to read volume tags. It is
set in the start-up and should not be changed. Most SCSI
robots will reject commands asking for volume tags when the
medium-changer doesn't support them.
o robot_device_type - This field is only used by the OpenVMS
implementation of MRD to indicate the method the host uses
to communicate with the medium-changer. This value is used
internally by the OpenVMS MRD code to select the appropriate
communcation path.
o ptm_addr and ptm_type The TL820 family supports a pass-through
mechanism (PTM) for moving cartridges from the inport to
the bar-code reader station or from there to the outport. In
multi-tower configurations the pass-through moves cartridges
from one tower to another. The MRD uses the PTM to perform
bar-code verification. Early versions of the TL820 family
firmware present the PTM as a Import/Export element, while
later versions may present it as a Transport. These fields are
used to indicate the address and type.
o maxecnt - The OpenVMS drivers used to communicate with medium-
changers support a limited I/O size that restricts the amount
of data that can be transferred by a Read Element Status
command. This field is used by the OpenVMS implementation
of MRD to know where large transfers must be broken up by the
software.
o element_desc - In addition to knowing the maximum number of
elements that may be read in a single Read Element Status
command, the element descriptor size is also needed to
correctly break-up command. This field stores the element
descriptor size on all implementations of the MRD.
The following fields are filled in from Element Address
Assignment Page obtained via the SCSI Mode Sense command. When
the robot is not a SCSI connect device, a suitable lie is filled
by the operating system specific code supporting that type of
robot.
o slot_count - This is the number of storage elements (slots) in
the medium-changer. Some robots (TLZ7L) will change the number
of slots presented depending on the type of magazine used. To
detect changes in the size of the carrier, mrd_startup(3mrd)
must be called and field checked for a change of value. When
no magazine is in the drive, it may report 0 slots.
o slot_start - This is the element address of the first storage
element. It is used by MRD to convert zero-relative element
addresses to the actual element address used by the medium-
changer.
o device_count - This is the number of data transfer elements
(drives) in the medium-changer. Like storage elements it may
be subject to change after a robot has been started.
o device_start - This is the element address of the first data
transfer element. It is used by MRD to convert zero-relative
element addresses to the actual element address used by the
medium-changer.
o port_count - This is the number of import/export elements
(ports) in the medium-changer. Like storage elements it may be
subject to change after a robot has been started.
o port_start - This is the element address of the first import
/export element. It is used by MRD to convert zero-relative
element addresses to the actual element address used by the
medium-changer.
o transport_count - This is the number of medium transport
elements (transports) in the medium-changer. Like storage
elements it may be subject to change after a robot has been
started.
o transport_start - This is the element address of the first
medium transport element. it is used by MRD to convert zero-
relative element addresses to the actual element address used
by the medium-changer.
o inport_count and outport_count - MRD V1.2 and earlier attempts
to identify ports according to whether they are used for
import-only, export-only or both. This is an artifact from
the time that the TL820 was the only supported medium- changer
with ports. Even though the TL810 has four ports these fields
will report it having four inports and four outports.
o inport_start and outport_start - MRD V1.2 and earlier assumes
that the arrangement of ports in the address space of the
medium-changer has all the inports together and all the
outports together. However, the two groups may be separated.
No guarantee is made whether the addressees of the inports
come before or after the outports. When the starting address
of both types of ports the same value, it can be safely
assumed that all the ports within the particular port count
are both inport and outport elements.
The following fields are obtained as the result of a SCSI Inquiry
Command. When the robot isn't a SCSI connected device, a suitable
lie is filled in by the operating system specific code supporting
that type of robot.
o scsi_info - These are the first eight (8) bytes of the SCSI
Inquiry data for the robot. MRD doesn't make use of this
information, but it is available if the calling application
wants to use it. These bytes will be zero on non-SCSI devices.
o inquiry - This is the VendorID, ProductID and
ProductRevisionLevel fields of the SCSI Inquiry data. They
are collected as a single NULL terminated string. The data is
edited to replace any non-printable character with a space.
These fields are not currently used:
o bus
o target
o lun
o devcap
o transport_geometry