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 <datestamp> to which taper replies with: TAPE-OK or, for fatal errors, with: TAPE-ERROR [<message>]
- driver will ask the taper to start a new tape with the NEW-TAPE command.
- driver can ask taper to copy a file from the holding disk to tape: FILE-WRITE <handle> <filename> <host> <disk> <level> or directly from a dumper: PORT-WRITE <handle> <host> <disk> <level> 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 the copy to tape finishes correctly taper replies with: DONE <handle> [<message>]
- If something goes wrong with the tape, taper can ask to continue on a new tape SPLIT-NEEDNEXT (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 data
data |
description
|
<datestamp> |
Date as "yymmdd"
|
<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
|
<message> |
Error or Status message
|
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
|
SPLIT-CONTINUE |
A complete part is written to tape
|
SPLIT-NEEDNEXT |
Ask driver if it should continue on 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)
|
ask for new tape
|
NEW-TAPE |
---> |
|
driver tell the taper to use a new tape
|
|
<--- |
GOT-NEW-TAPE |
taper found one
|
|
<--- |
NO-NEW-TAPE |
no tape are available
|
file-write setup
|
FILE-WRITE |
---> |
|
|
|
|
|
Will get one part-result for each part written and one global result
|
port-write setup
|
PORT-WRITE |
---> |
|
|
|
<--- |
PORT |
|
|
|
|
Will continue with one part-result for each part written and one global result
|
global-result
|
|
<--- |
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)
|
part-result
|
|
<--- |
SPLIT-CONTINUE |
successfully part written to tape
|
|
<--- |
SPLIT-NEEDNEXT |
failed PART (only for tape-error) (driver will send a NEW-TAPE or NO-NEW-TAPE command)
|
no new tape
|
NO-NEW-TAPE |
---> |
|
driver doesn't want the taper to use a new tape (continue with global-result)
|