The OpenNET Project / Index page

[ новости /+++ | форум | wiki | теги | ]

Интерактивная система просмотра системных руководств (man-ов)

 [Cписок руководств | Печать]

ch (4)
  • >> ch (4) ( FreeBSD man: Специальные файлы /dev/* )

  • BSD mandoc


     - SCSI media-changer (juke box) driver


    device ch device ch1 target 4 unit 0  


    The driver provides support for a SCSI media changer. It allows many slots of media to be multiplexed between a number of drives. The changer device may optionally be equipped with a bar code reader, which reads label information attached to the media.

    A SCSI adapter must also be separately configured into the system before a SCSI changer can be configured.

    As the SCSI adapter is probed during boot, the SCSI bus is scanned for devices. Any devices found which answer as 'Changer' type devices will be 'attached' to the driver. In Fx releases prior to 2.1, the first found will be attached as ch0 and the next, ch1 etc. Beginning in 2.1 it is possible to specify what ch unit a device should come on line as; refer to scsi(4) for details on kernel configuration.  


    In configuring, if an optional count is given in the specification, that number of SCSI media changers are configured; Most storage for them is allocated only when found so a large number of configured devices is cheap. (once the first has included the driver).  


    User mode programs communicate with the changer driver through a number of ioctls which are described below. Changer element addresses used in the communication between the kernel and the changer device are mapped to zero-based logical addresses. Element types are specified as follows:

    Medium transport element (picker).
    Storage element (slot).
    Import/export element (portal).
    Data transfer element (drive).

    The following ioctl(2) calls apply to the changer. They are defined in the header file In sys/chio.h .

    (Vt struct changer_move ) Move a medium from one element to another (MOVE MEDIUM ) using the current picker. The source and destination elements are specified in a changer_move structure, which includes at least the following fields:
    u_int cm_fromtype; /* element type to move from */
    u_int cm_fromunit; /* logical unit of from element */
    u_int cm_totype;   /* element type to move to */
    u_int cm_tounit;   /* logical unit of to element */
    u_int cm_flags;    /* misc. flags */
    If the CM_INVERT in the cm_flags field is set, the medium changer is instructed to flip the medium while moving it.
    (Vt struct changer_exchange ) Move the medium located in the source element to the first destination element, and move the medium that had been in the first destination element to the second destination element. In case of a simple exchange, the source and second destination elements should be the same. The current picker is used to perform the operation. The addresses of the affected elements is specified to the ioctl in a Vt changer_exchange structure which includes at least the following fields:
    u_int ce_srctype;        /* element type of source */
    u_int ce_srcunit;        /* logical unit of source */
    u_int ce_fdsttype; /* element type of first destination */
    u_int ce_fdstunit; /* logical unit of first destination */
    u_int ce_sdsttype; /* element type of second destination */
    u_int ce_sdstunit; /* logical unit of second destination */
    u_int ce_flags;  /* misc. flags */
    In ce_flags CM_INVERT1 and/or CM_INVERT2 may be set to flip the first or second medium during the exchange operation, respectively.

    This operation is untested

    (Vt struct changer_position ) Position the current picker in front of the specified element. The element is specified with a changer_position structure, which includes at least the following elements:
    u_int cp_type;  /* element type */
    u_int cp_unit;  /* logical unit of element */
    u_int cp_flags; /* misc. flags */
    The cp_flags field may be set to CP_INVERT to invert the picker during the operation.
    (Vt int ) Return the logical address of the current picker.
    (Vt int ) Select the picker specified by the given logical address.
    (Vt struct changer_params ) Return the configuration parameters for the media changer. This ioctl fills the changer_params structure passed by the user with at least the following fields:
    u_int cp_npickers; /* number of pickers */
    u_int cp_nslots;   /* number of slots */
    u_int cp_nportals; /* number of import/export portals */
    u_int cp_ndrives;  /* number of drives */

    This call can be used by applications to query the dimensions of the jukebox before using the CHIGSTATUS ioctl to query the jukebox' status.

    Perform the INITIALIZE ELEMENT STATUS call on the media changer device. This forces the media changer to update its internal status information with respect to loaded media. It also scans any barcode labels provided that it has a label reader. The driver's status is not affected by this call.
    (Vt struct changer_element_status_request ) Perform the READ ELEMENT STATUS call on the media changer device. This call reads the element status information of the media changer and converts it to an array of Vt changer_element_status structures.

    With each call to CHIOGSTATUS the status of one or more elements of one type may be queried.

    The application passes a Vt changer_element_status_request structure to the driver which contains the following fields:

    u_int                          cesr_element_type;
    u_int                          cesr_element_base;
    u_int                          cesr_element_count;
    u_int                          cesr_flags;
    struct changer_element_status *cesr_element_status;

    This structure is read by the driver to determine the type, logical base address and number of elements for which information is to be returned in the array of Vt changer_element_status structures pointed to by the cesr_element_status field The application must allocate enough memory for cesr_element_count status structures (see below). The cesr_flags can optionally be set to CESR_VOLTAGS to indicate that volume tag (bar code) information is to be read from the jukebox and returned.

    The cesr_element_base and cesr_element_count fields must be valid with respect to the physical configuration of the changer. If they are not, the CHIOGSTATUS ioctl returns the Er EINVAL error code.

    The information about the elements is returned in an array of Vt changer_element_status structures. This structure include at least the following fields:

    u_int            ces_addr;      /* element address in media changer */
    u_char           ces_flags;     /* see CESTATUS definitions below */
    u_char           ces_sensecode; /* additional sense code for element */
    u_char           ces_sensequal; /* additional sense code qualifier */
    u_char           ces_invert;    /* invert bit */
    u_char           ces_svalid;    /* source address (ces_source) valid */
    u_short          ces_source;    /* source address of medium */
    changer_voltag_t ces_pvoltag;   /* primary volume tag */
    changer_voltag_t ces_avoltag;   /* alternate volume tag */
    u_char           ces_idvalid;   /* ces_scsi_id is valid */
    u_char           ces_scsi_id;   /* SCSI id of element (if ces_idvalid is nonzero) */
    u_char           ces_lunvalid;  /* ces_scsi_lun is valid */
    u_char           ces_scsi_lun;  /* SCSI lun of element (if ces_lunvalid is nonzero) */

    The ces_addr field contains the address of the element in the coordinate system of the media changer. It is not used by the driver, and should be used for diagnostic purposes only.

    The following flags are defined for the ces_flags field:

    A medium is present.
    The medium has been deposited by the operator (and not by a picker).
    The element is in an exceptional state (e.g. invalid barcode label, barcode not yet scanned).
    The element is accessible by the picker.
    The element supports medium export.
    The element supports medium import.

    Note that not all flags are valid for all element types.



    This version of the driver has been tested with a DEC TZ875 (5 slot, one DLT drive) and a Breece Hill Q47 (60 slot, four DLT drives, barcode reader).

    Many of the features the driver supports are not thoroughly tested due to the fact that the devices available for testing do not support the necessary commands. This is true for alternate volume tags, media flipping, import/export element handling, multiple picker operation and other things.  


    device entries



    If the media changer does not support features requested by the driver, it will produce both console error messages and failure return codes to the ioctls described here.  


    chio(1), cd(4), da(4), sa(4)  


    The driver appeared in BSD 386 0.1  


    An -nosplit The driver was written by An Jason R. Thorpe Aq for And Communications, It was added to the system by An Stefan Grefen Aq who apparently had such a device. It was ported to CAM by An Kenneth Merry Aq . It was updated to support volume tags by An Hans Huebner Aq .




    Поиск по тексту MAN-ов: 

    Inferno Solutions
    Hosting by

    Закладки на сайте
    Проследить за страницей
    Created 1996-2023 by Maxim Chirkov
    Добавить, Поддержать, Вебмастеру