spec.v1.txt

网络数据管理协议的开发

Request Arguments


   device                Name of tape device to open.


   mode                  Tape open mode.


Reply Arguments


   error                 Error code.


Reply Errors


   NDMP_NO_ERR           Tape device successfully opened.


   NDMP_DEVICE_OPENED_ERRThe NDMP server already has a SCSI device or tape
                         device open.




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   NDMP_NO_DEVICE_ERR    The specified device does not exist.


   NDMP_DEVICE_BUSY_ERR  The device is already open by another NDMP server
                         or system process.


   NDMP_IO_ERR           Device I/O error.


   NDMP_WRITE_PROTECT_ERRDevice can not be opened in write mode because
                         the tape is write protected.


   NDMP_NO_TAPE_LOADED_ERR    No tape loaded in the tape device.


3.4.2 Close Device

Close the tape drive. Drive can be opened by others. No further requests
can be processed until another open request is successfully executed.


Message XDR definition



   /* No request message body. */

   struct ndmp_tape_close_reply
   {
       ndmp_error          error;
   };




Request Arguments


   This message does not have a message body.


Reply Arguments


   error                 Error code.


Reply Errors



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   NDMP_NO_ERR           Tape device successfully closed.


   NDMP_DEV_NOT_OPEN_ERR No tape device currently open by the connection.


   NDMP_IO_ERR           Device I/O error.


3.4.3 Get Tape State

Return the state of the tape drive interface.


Message XDR definition



   /* No request message body. */

   struct ndmp_u_quad
   {
       u_long  high;
       u_long  low;
   };

   /* flags */
   const NDMP_TAPE_NOREWIND    = 0x0008;
   const NDMP_TAPE_WR_PROT     = 0x0010;
   const NDMP_TAPE_ERROR       = 0x0020;
   const NDMP_TAPE_UNLOAD      = 0x0040;

   struct ndmp_tape_get_state_reply
   {
       ndmp_error          error;
       u_long              flags;
       u_long              file_num;
       u_long              record_num;
       u_long              record_size;
       u_long              soft_errors;
       u_long              block_size;
       u_long              blockno;
       ndmp_u_quad         total_space;
       ndmp_u_quad         space_remain;
   };




Request Arguments



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   This message does not have a message body.


Reply Arguments


   error                 Error code.


   Flags                 Bitmask of the following tape device mode flags:


         NDMP_TAPE_NOREWIND   Upon device close, the tape will not be
                         rewound.


         NDMP_TAPE_WR_PROT    The loaded tape is write-protected.


         NDMP_TAPE_ERROR A media error was detected during the previous
                         tape operation. This bit is cleared at the start
                         of each tape operation.


         NDMP_TAPE_UNLOADThe currently loaded tape will automatically be
                         unloaded when the device is closed. Only applies
                         to media changer devices such as tape stackers
                         and jukeboxes.


   file_num              Current file position. First file on the tape is
                         file number 0.


   record_num            Current record position. First record in a file
                         is record number 0.


   record_size           Tape record size in bytes.


   soft_errors           Total number of soft media errors detected since
                         the device was opened.


   block_size            Tape block size in bytes. 0 if the device is not
                         a fixed block device.


   blockno               Current tape block number. First tape block is
                         block number 0.


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   total_space           Total tape capacity in bytes. 0 if this feature
                         not supported by the NDMP server implementation.


   space_remain          Total remaining tape capacity in bytes. 0 if this
                         feature not supported by the NDMP server
                         implementation.


Reply Errors


   NDMP_NO_ERR           Tape state successfully returned.


   NDMP_DEV_NOT_OPEN_ERR No tape device currently open by the connection.


   NDMP_IO_ERR           Device I/O error.


3.4.4 MTIO

Provides access to the standard magnetic tape I/O operations.   When
spacing forward over a record, the tape head is positioned in the tape gap
between the record just skipped and the next record. When spacing forward
over file marks, the tape head is positioned in the tape gap between the
next file mark and the record that follows it. When spacing backward over
a record data, the tape head is positioned in the tape gap immediately
preceding the tape record where the tape head is currently positioned.
When spacing backward over file marks, the tape head is positioned in the
tape gap preceding the file mark the next read would fetch the EOF.


Message XDR definition


















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   enum ndmp_tape_mtio_op
   {
       NDMP_MTIO_FSF,
       NDMP_MTIO_BSF,
       NDMP_MTIO_FSR,
       NDMP_MTIO_BSR,
       NDMP_MTIO_REW,
       NDMP_MTIO_EOF,
       NDMP_MTIO_OFF
   };

   struct ndmp_tape_mtio_request
   {
       ndmp_tape_mtio_op   tape_op;
       u_long              count;
   };

   struct ndmp_tape_mtio_reply
   {
       ndmp_error          error;
       u_long              resid_count;
   };




Request Arguments


   tape_op               One of the following tape operations:


     NDMP_MTIO_FSF       Forward space over file marks. The tape head is
                         positioned in the tape gap between the file mark
                         and the record that follows it.


     NDMP_MTIO_BSF       Backward space over file marks. The tape head is
                         positioned in the tape gap preceeding the file
                         mark such that the next read encounters EOF.


     NDMP_MTIO_FSR       Forward space over tape records. The tape head is
                         positioned in the tape gap between the record
                         just skipped and the next record.






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     NDMP_MTIO_BSR       Backward space over tape records. The tape head
                         is positioned in the tape gap preceeding the tape
                         record just skipped.


     NDMP_MTIO_REW       Rewind the tape.


     NDMP_MTIO_EOF       Write end of file marks.


     NDMP_MTIO_OFF       Eject the tape from the device.


   count                 Number of operations to perform.


Reply Arguments


   error                 Error code.


   resid_count           Residual operation count. Represents the number
                         of operations that were not able to be performed
                         due to encountering beginning of tape, end of
                         tape, end of written media, or a tape error.


Reply Errors


   NDMP_NO_ERR           Tape operation successfully completed.


   NDMP_DEV_NOT_OPEN_ERR No tape device currently open by the connection.


   NDMP_IO_ERR           Device I/O error.


   NDMP_ILLEGAL_ARGS_ERR Invalid tape operation specified.


   NDMP_WRITE_PROTECT_ERRTape is write protected.


3.4.5 Write

Writes data to the tape device. The NDMP server writes the specified data
as a single record. It is the responsibility of the NDMP client to ensure


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that the length of the data is a multiple of the tape device block size if
the device is a fixed block device. The NDMP server performs no buffering
or padding of the data. . This request is typically used by the NDMP
client to write tape header and trailer file data.


Message XDR definition



   struct  ndmp_tape_write_request
   {
       opaque              data_out<>;
   };

   struct  ndmp_tape_write_reply
   {
       ndmp_error          error;
       u_long              count;
   };




Request Arguments


   data_out              The data to be written to the tape device.


Reply Arguments


   error                 Error code.


   count                 Number of data bytes written..


Reply Errors


   NDMP_NO_ERR           All data successfully written to the tape device.


   NDMP_DEV_NOT_OPEN_ERR No tape device currently open by the connection.


   NDMP_IO_ERR           Device I/O error.




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   NDMP_WRITE_PROTECT_ERRTape is write protected.


   NDMP_EOM_ERR          End of tape was encountered while writing.


3.4.6 Read

Reads data from the tape drive. The NDMP server always reads a complete
record. It is the responsibility of the NDMP client to specify a length
that is greater that or equal to the size of the record to be read. An
attempt to read less than a full record will result in an I/O error. This
request is typically used by the NDMP client to read tape header and
trailer file data.


Message XDR definition



   struct  ndmp_tape_read_request
   {
       u_long              count;
   };

   struct  ndmp_tape_read_reply
   {
       ndmp_error          error;
       opaque              data_in<>;
   };




Request Arguments


   count                 Number of bytes to read.


Reply Arguments


   error                 Error code.


   data_in               The data read from the tape drive. The returned
                         number of bytes may be less than the number
                         requested if the requested amount was larger than
                         the read tape record.



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Reply Errors


   NDMP_NO_ERR           Data successfully read from the tape device.


   NDMP_DEV_NOT_OPEN_ERR No tape device currently open by the connection.


   NDMP_IO_ERR           Device I/O error during read.


   NDMP_EOF_ERR          End of file was encountered while reading. The
                         number of returned  data bytes may be less than
                         the number of bytes requested.





3.4.7 Set Record Size

Sets the tape record size used when writing/reading the tape during
backup/recover operations. Note that the tape record size has no effect on
the ndmp_tape_write and ndmp_tape_read requests.


Message XDR definition



   struct  ndmp_tape_set_record_size_request
   {
       u_long              len;
   };

   struct  ndmp_tape_set_record_size_reply
   {
       ndmp_error          error;
   }




Request Arguments


   len                   Tape record size in bytes.





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Reply Arguments


   error                 Error code.


Reply Errors


   NDMP_NO_ERR           Tape record size successfully set.