HPUX scsi_change[7]
scsi_changer(7) Series 700 Only scsi_changer(7)
NAME
scsi_changer - SCSI media changer device driver
DESCRIPTION
SCSI media changer devices mechanically move media between storage and
usage locations. Each potential media location has a specific element
address and is one of the following element types:
storage A location to hold a unit of media not
currently in use. Typically most media will
be located in this type of element.
import/export A location for inserting and removing media
from the device. Movement of a unit of media
to this type of location is in effect an
eject operation. Movement of a unit of media
from this type of location is a load
operation.
data transfer A location for accessing media data. This is
generally the location of a device that reads
and/or writes data on the media being handled
by the media changer device. Movement to
this type of location is a physical-media-
mount operation. Movement from this type of
location is a physical-media-unmount
operation.
media transport A location for media movement. Media is
generally temporarily located in this type of
element only during actual media movement.
The SIOC_INIT_ELEM_STAT ioctl causes the media changer device to take
inventory. As a result, the media changer device determines the
status of each and every element address, including the presence or
absence of a unit of media.
The element addresses supported by a media changer device can be
determined by use of the SIOC_ELEMENT_ADDRESSES ioctl. The first
valid element address and the number of elements is indicated for each
element type. These element addresses may be used as source and
destination location arguments.
The SIOC_ELEMENT_STATUS ioctl indicates the status of an element. The
element address for which status information is requested is specified
via the element field. The resulting status data indicates the
presence or absence of a unit of media in that element address as well
as other information.
The SIOC_RESERVE and SIOC_RELEASE ioctls control access to element
addresses. Depending on the device, reservations may limit operator
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control of those element addresses in the media changer device.
Specific element addresses can be reserved to handle interlocking
between multiple requesters if each requester has a unique reservation
identification. The value zero in the all_elements field specifies
that a single element address should be reserved or released. An
element address reserved in this manner can not be reserved by another
single element address reservation using a different reservation
identification. The reservation field specifies the reservation
identification. The element field specifies the element address to be
reserved.
The value ``1'' in the all_elements field indicates that all element
addresses should be reserved. The reservation and element fields
should contain the value zero since these fields are not meaningful
when reserving all element addresses. Reserving all element addresses
is primarily useful for limiting operator control.
The SIOC_MOVE_MEDIUM and SIOC_EXCHANGE_MEDIUM ioctls reposition
unit(s) of media. Depending of the source and destination element
types, this may result in a media load, eject, mount, unmount, or
simple repositioning. Media can be ``flipped'' using values of ``1''
in the invert, invert_first, or invert_second fields. The
SIOC_EXCHANGE_MEDIUM ioctl repositions two different units of media.
One unit of media is moved from the element specified by the source
field to the element specified by the first_destination field. A
second unit of media is moved from the element specified by the
first_destination field to the element specified by the
second_destination field. An exchange occurs if the source and
second_destination fields are the same.
The following is included from <sys/scsi.h>:
#define SIOC_INIT_ELEM_STAT _IO('S', 51)
#define SIOC_ELEMENT_ADDRESSES _IOW('S', 52, struct element_addresses)
#define SIOC_ELEMENT_STATUS _IOWR('S', 53, struct element_status)
#define SIOC_RESERVE _IOW('S', 54, struct reservation_parms)
#define SIOC_RELEASE _IOW('S', 55, struct reservation_parms)
#define SIOC_MOVE_MEDIUM _IOW('S', 56, struct move_medium_parms)
#define SIOC_EXCHANGE_MEDIUM _IOW('S', 57, struct exchange_medium_parms)
/* structure for SIOC_INIT_ELEM_STAT ioctl */
struct element_addresses {
unsigned short first_transport;
unsigned short num_transports;
unsigned short first_storage;
unsigned short num_storages;
unsigned short first_import_export;
unsigned short num_import_exports;
unsigned short first_data_transfer;
unsigned short num_data_transfers;
};
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/* structure for SIOC_ELEMENT_STATUS ioctl */
struct element_status {
unsigned short element; /* element address */
unsigned char full:1; /* holds a a unit of media */
unsigned char reserved:1; /* is currently reserved */
unsigned char except:1; /* is in an abnormal state */
unsigned char access:1; /* transport element accessible */
unsigned char export_enable:1; /* allows media removal (eject) */
unsigned char import_enable:1; /* allows media insertion (load) */
unsigned char resv1:2;
unsigned char resv2;
unsigned char sense_code; /* info. about abnormal state */
unsigned char sense_qualifier; /* info. about abnormal state */
unsigned char not_bus:1; /* transfer device SCSI bus differs */
unsigned char resv3:1;
unsigned char id_valid:1; /* bus_address is valid */
unsigned char lu_valid:1; /* lun is valid */
unsigned char resv4:1;
unsigned char lun:3; /* transfer device SCSI LUN */
unsigned char bus_address; /* transfer device SCSI address */
unsigned char resv4;
unsigned char resv5:6;
unsigned char invert:1; /* media in element was inverted */
unsigned char source_valid:1; /* source_element is valid */
unsigned short source_element; /* last storage location of medium */
char pri_vol_tag[36]; /* volume tag (device optional) */
char alt_vol_tag[36]; /* volume tag (device optional) */
unsigned char misc_bytes[168]; /* device specific */
};
/* structure for SIOC_RESERVE and SIOC_RELEASE ioctls */
struct reservation_parms {
unsigned short element;
unsigned char identification;
unsigned char all_elements;
};
/* structure for SIOC_MOVE_MEDIUM ioctl */
struct move_medium_parms {
unsigned short transport;
unsigned short source;
unsigned short destination;
unsigned char invert;
};
/* structure for SIOC_EXCHANGE_MEDIUM ioctl */
struct exchange_medium_parms {
unsigned short transport;
unsigned short source;
unsigned short first_destination;
unsigned short second_destination;
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unsigned char invert_first;
unsigned char invert_second;
};
WARNING
Some media changer devices do not support the SIOC_INIT_ELEM_STAT and
SIOC_ELEMENT_STATUS ioctls. For some of these devices, it may be
possible to determine the full or empty status of an element address
by attempting media movement using that element address as both the
source and destination arguments of a media movement operation.
Many media changer devices do not support the SIOC_EXCHANGE_MEDIUM
ioctl. For these devices, multiple SIOC_MOVE_MEDIUM ioctl operations
may be used to accomplish the same results, provided a suitable
temporary element address may be found.
SEE ALSO
scsi(7), autochanger(7), mknod(1M).
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