[Debburn-devel] wodim timeout too short for DVD+R DL

[Thomas Schmitt]

Hi,

a problem examination on cdwrite mailing list yielded that the default
timeout of wodim with DVD+R DL media and command RESERVE TRACK
does not suffice for some drives.

A failed run with SCSI log is posted at
  http://lists.debian.org/cdwrite/2010/11/msg00045.html

The decisive part of the log is:
> Executing 'reserve track' command on Bus 2 Target 0, Lun 0 timeout 40s
> CDB:  53 00 00 00 00 00 0C 65 40 00
> Errno: 5 (Input/output error), reserve track scsi sendcmd: retryable error
> CDB:  53 00 00 00 00 00 0C 65 40 00
> status: 0x0 (GOOD STATUS)
> cmd finished after 43.701s timeout 40s
> wodim: Cannot open new session.


I now got the confirmation from Zhang Weiwu that wodim succeeds on the
problematic drive if option
  timeout=200
is given.
Actually timeout=45 would have sufficed. The successful run logs

> Executing 'reserve track' command on Bus 2 Target 0, Lun 0 timeout 200s
> CDB:  53 00 00 00 00 00 0C 65 40 00
> cmd finished after 43.458s timeout 200s

It seems that the Linux kernel did not interrupt the long running
command but just indicated error afterwards.
So a short timeout seems not to be of much benefit anyway.

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Another flaw that showed up:

wodim silently ignores option -multi with DVD+R DL.
If it cannot keep the media open then it should refuse to start with -multi.

Keeping a DVD+R appendable is just a matter of sending CLOSE TRACK SESSION
Close Function 010b rather than 100b or 101b.

wodim sends Close Function 100b which works fine,

> Executing 'close track/session' command on Bus 2 Target 0, Lun 0 timeout 1000s
> CDB:  5B 00 04 00 00 00 00 00 00 00
> cmd finished after 117.955s timeout 1000s

and then Close Function 101b which fails:

> Executing 'close track/session' command on Bus 2 Target 0, Lun 0 timeout 1000s
> CDB:  5B 00 05 00 00 00 00 00 00 00
> Errno: 5 (Input/output error), close track/session scsi sendcmd: no error
> CDB:  5B 00 05 00 00 00 00 00 00 00
> status: 0x2 (CHECK CONDITION)
> Sense Bytes: 70 00 05 00 00 00 00 0A 00 00 00 00 24 00 00 00
> Sense Key: 0x5 Illegal Request, Segment 0
> Sense Code: 0x24 Qual 0x00 (invalid field in cdb) Fru 0x0

It appears that only one of these two should be applied.
100b does not apply to single layer DVD+R.

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Have a nice day :)

Thomas