Driver-Taper protocol

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Contents

Communication method

driver talks via two pipes connected to taper's stdin and stdout. The commands and responses are plain text.

Command sequence during backup operation

  • driver initialises taper with: START-TAPER <timestamp> to which taper replies with: TAPE-OK or, for fatal errors, with: TAPE-ERROR [<message>]. For speed up,taper is authorized to scan the library and find a valid tape after it received the START-TAPER command.
  • driver can ask taper to copy a file from the holding disk to tape (FILE-WRITE) or directly from a dumper (PORT-WRITE) or exit at the end of the run (QUIT).
  • taper responds to the PORT-WRITE command with:
    • PORT <hdr-port> <ip-port-pairs> which the driver should then hand on to dumper in a PORT-DUMP command
  • if taper has no tape in use, it reply with REQUEST-NEW-TAPE.
  • If the copy to tape finishes correctly taper replies with DONE.
  • If something goes wrong with the tape, taper can ask to continue on a new tape REQUEST-NEW-TAPE (for splited dump only) or it can abort that dump with PARTIAL or FAILED reply
  • After any dump that finished in PARTIAL or FAILED with a TAPE-ERROR, the driver must send a NEW-TAPE before issuing another *-WRITE command.

Other commands

  • If driver says something that taper doesn't recognise it responds with: BAD-COMMAND <message>
  • taper responds to the QUIT command with: QUITING

Protocol command reference

Taper command reply

ReplyDescription
TAPE-OKtaper is setup correctly
TAPE-ERRORError in setup of the driver
PORTReply sent in response to PORT-WRITE command
DONEFull dump is on the media
PARTIALDump was partially written to the media.
FAILEDNothing was written to the media
DUMPER-STATUSAsk driver to send the dumper status
PARTDONEA complete part is written to tape
REQUEST-NEW-TAPEAsk driver if it should use a new tape
NEW-TAPEWill continue on a new found tape
NO-NEW-TAPEWill not continue on a new tape


DONE/PARTIAL and FAILED reply also contains an INPUT-* an TAPE-* message to denote any error:

ReplyDescription
INPUT-GOODThere was no error with the input.
INPUT-ERRORThere was error with the input.
ReplyDescription
TAPE-GOODThis tape can be use to write another dump.
TAPE-ERRORNothing more can fit on that tape.

A result for a successful dump should be: DONE INPUT-GOOD TAPE-GOOD

Driver/Taper Requests/Replies

Driver request Taper replyDescription
initiall setup
START-TAPER--->
<---TAPER-OKnormal taper setup (a tape is available, nothing is written on it)
<---TAPE-ERRORfailed taper setup (no tape are available or something else is broken)
file-write setup
FILE-WRITE--->
<---REQUEST-NEW-TAPE (Optional) ask driver if we should start this dump on a new tape. (driver will send a NEW-TAPE or NO-NEW-TAPE command)
Will get one part-result for each part written and one global result
port-write setup
PORT-WRITE--->
<---PORT(taper accepts a connection on the hdr-port, reads the full header, closes the connection, and then accepts a connection on one of the directtcp ip:ports)
<---REQUEST-NEW-TAPE(Optional) ask driver if we should start this dump on a new tape. (driver will send a NEW-TAPE or NO-NEW-TAPE command)
Will continue with one part-result for each part written and one global result
global-result
Can ask-dumper-status (Should be done if taper detect no error (INPUT-GOOD and TAPE-GOOD)
<---DONE INPUT-GOOD TAPE-GOODnormal protocol for a success
<---PARTIAL INPUT-* TAPE-*protocol for error in data phase (something written to tape)
<---FAILED INPUT-* TAPE-*protocol for error in setup (before something is written to tape)
ask-dumper-status
<---DUMPER-STATUSAsk driver the dumper status
DONE--->Dumper succeeded
FAILED--->Dumper failed
part-result
<---PARTDONEsuccessfully part written to tape
<---REQUEST-NEW-TAPEWe get a tape error, ask the driver if we can use a new tape (driver will send a NEW-TAPE or NO-NEW-TAPE command)
driver don't want the taper to use a new tape
NO-NEW-TAPE--->driver doesn't want the taper to use a new tape (continue with global-result)
driver want the taper to use a new tape
NEW-TAPE--->driver want the taper to use a new tape
<---NEW-TAPEtaper found one
<---NO-NEW-TAPEno tape are available
quit
QUIT--->taper quits

Command/reply arguments

Protocol data

datadescription
<timestamp>Time as "yymmdd" of "yymmddhhmmss"
<worker_name>The name of a worker
<handle>Request ID
<filename>Name of file on the holding disk where backup will be written to
<port> Taper port to send the backup data to
<host> Hostname of the client
<disk> Disk on the client being backed up
<level> Dump level being used for backup
splitsize size of each part on tape in bytes
split_diskbuffer directory in which to create disk buffer files, or the literal string "NULL" if none is specified
<message> Error or Status message

driver command

  • START-TAPER worker_name timestamp
  • PORT-WRITE worker_name handle hostname diskname level datestamp dle_tape_splitsize dle_split_diskbuffer dle_fallback_splitsize dle_allow_split part_size part_cache_type part_cache_dir part_cache_max_size datapath
    • if there is no split_diskbuffer, then it is specified as the string "NULL"
    • splitsize and fallback_splitsize, both in kb, come directly from the dumptype
  • FILE-WRITE worker_name handle filename hostname diskname level datestamp dle_tape_splitsize dle_split_diskbuffer dle_fallback_splitsize dle_allow_split part_size part_cache_type part_cache_dir part_cache_max_size orig_kb
  • START-SCAN worker_name handle
  • TAKE-SCRIBE-FROM worker_name handle from_worker_name
  • DONE worker_name handle (result from dumper send to taper)
  • FAILED worker_name handle (result from dumper send to taper)
  • NEW-TAPE worker_name
  • NO-NEW-TAPE worker_name "reason"
  • QUIT

handles are unique to each DLE during a run, but since the taper only operates on a single file at a time, they are generally useless to the taper except in constructing syntactically correct responses to the driver.

the dle_* and part_* parameters are taken directly from the corresponding dumptype and tapetype configuration parameters

taper reply

  • TAPER-OK worker_name
  • TAPE-ERROR worker_name "error-message"
  • PARTIAL handle INPUT-* TAPE-* "[sec %f kb %d kps %f]" "input-error-message" "tape-error-message"
    • The statistic are the sum of all successful part (PARTDONE), it should not include the failed part.
  • DONE handle INPUT-GOOD TAPE-GOOD "[sec %f kb %d kps %f]" "" ""
    • The statistic are the sum of all successful part (PARTDONE), it should not include the failed part.
  • FAILED handle INPUT-* TAPE-* "input-error-message" "tape-error-message"
  • NEW-TAPE handle label
  • NO-NEW-TAPE handle
  • PARTDONE handle label fileno kb "[sec %f kb %d kps %f]"
    • yep, the kb are specified twice
  • REQUEST-NEW-TAPE handle
  • PORT worker_name handle hdr-port ip-port-pairs
  • BAD-COMMAND "error message"
  • DUMPER-STATUS handle

LOG

  • One PART or PARTPARTIAL log line for all part written to tape. It tell the location and status of each part.
    • PART taper label fileno hostname diskname timestamp part-number/totpart level [sec %f kb %d kps %f]
    • PARTPARTIAL taper label fileno hostname diskname timestamp part-number/totpart level [sec %f kb %d kps %f] "error message"

totpart should be -1 if the the number is not known (PORT-WRITE)

  • One DONE/PARTIAL/FAILED for each dump. It tell the status of the complete dump.
    • DONE taper hostname diskname timestamp totpart level [sec %f kb %d kps %f]
      • The statistic is the sum of all successful part (PART), it doesn't include PARTPARTIAL
      • This indicates that, from the taper's perspective, the dump is completely done and should not be retried; this is the case even if the dumped file was partial
    • PARTIAL taper hostname diskname timestamp totpart level [sec %f kb %d kps %f] "error message"
      • The statistic is the sum of all successful part (PART), it doesn't include PARTPARTIAL
      • Some of the data was sent to the device, but not all of it; the driver will likely retry the dump
    • FAILED taper hostname diskname timestamp level "error message"
      • None of the data was sent to the device; the driver will likely retry the dump
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