Driver-Taper protocol
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 <port> which 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
Reply | Description |
---|---|
TAPE-OK | taper is setup correctly |
TAPE-ERROR | Error in setup of the driver |
PORT | Reply sent in response to PORT-WRITE command |
DONE | Full dump is on the media |
PARTIAL | Dump was partially written to the media. |
FAILED | Nothing was written to the media |
DUMPER-STATUS | Ask driver to send the dumper status |
PARTDONE | A complete part is written to tape |
REQUEST-NEW-TAPE | Ask driver if it should use a new tape |
NEW-TAPE | Will continue on a new found tape |
NO-NEW-TAPE | Will not continue on a new tape |
DONE/PARTIAL and FAILED reply also contains an INPUT-* an TAPE-* message to denote any error:
Reply | Description |
---|---|
INPUT-GOOD | There was no error with the input. |
INPUT-ERROR | There was error with the input. |
Reply | Description |
---|---|
TAPE-GOOD | This tape can be use to write another dump. |
TAPE-ERROR | Nothing 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 reply | Description | |
---|---|---|---|
initail setup | |||
START-TAPER | ---> | ||
<--- | TAPE-OK | normal taper setup (a tape is available, nothing is written on it) | |
<--- | TAPE-ERROR | failed 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 | ||
<--- | 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-GOOD | normal 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-STATUS | Ask driver the dumper status | |
DONE | ---> | Dumper succeeded | |
FAILED | ---> | Dumper failed | |
part-result | |||
<--- | PARTDONE | successfully part written to tape | |
<--- | REQUEST-NEW-TAPE | We 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 | |
<--- | GOT-NEW-TAPE | taper found one | |
<--- | NO-NEW-TAPE | no tape are available | |
quit | |||
QUIT | ---> | ||
<--- | QUITING |
Command/reply arguments
Protocol data
data | description |
---|---|
<timestamp> | Time as "yymmdd" of "yymmddhhmmss" |
<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 |
split_diskbuffer | file use to buffer a complete part |
<message> | Error or Status message |
driver command
- START-TAPER timestamp
- PORT-WRITE handle hostname diskname level datestamp splitsize split_diskbuffer fallback_splitsize
- FILE-WRITE handle filename hostname diskname level datestamp splitsize
- DONE handle (result from dumper send to taper)
- FAILED handle (result from dumper send to taper)
- NEW-TAPE handle
- NO-NEW-TAPE handle
- QUIT
taper reply
- TAPER-OK
- TAPE-ERROR [handle] "error-message"
- handle is specified only in some circumstances
- 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 port
- QUITTING
- BAD-COMMAND "error message"
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
- 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
- FAILED taper hostname diskname timestamp level "error message"
- DONE taper hostname diskname timestamp totpart level [sec %f kb %d kps %f]
algorithm after a part written to tape
if (successful part) { L_PART -> logfile if (splited dump) { PARTDONE -> DRIVER if (not splited dump || last part) { if (PORT-WRITE) { DUMPER-STATUS -> driver get dumper result from driver (FAILED|DONE) } if (partial) #from dumper status or partial flag in header { PARTIAL INPUT-GOOD TAPE-GOOD -> driver L_PARTIAL -> logfile } else (whole) { DONE INPUT-GOOD TAPE-GOOD -> driver L_SUCCESS -> logfile } } else #splited dump GOTO next part } else #failed part { if (something written to tape for this part) L_PARTPARTIAL -> logfile if (splitted dump and tape error && no-input-error) { SPLIT_NEEDNEXT -> driver L_INFO -> logfile #wait for driver NEW-TAPE or NO-NEW-TAPE #It could take a long time to get the result if(driver sent NEW-TAPE) if (new tape available) NEW-TAPE -> DRIVER GOTO retry that part to the new tape else #no valid writable tape found NO-NEW-TAPE -> DRIVER else #driver sent NO-NEW-TAPE noop } #it's possible to have both INPUT-* and TAPE-* error or none. if (nothing written to tape for this dump) { FAILED INPUT-* TAPE-* -> driver L_FAIL -> logfile } else #something written to tape for this dump { PARTIAL INPUT-* TAPE-* -> driver; L_PARTIAL -> logfile } }