[mythtv-users] Just lost a recorded file due to mythtranscode "renaming error"

Michael T. Dean mtdean at thirdcontact.com
Tue Jan 12 19:30:56 UTC 2010


On 01/12/2010 04:54 AM, Jeffrey J. Kosowsky wrote:
> mythbackend.log shows:
> 	2010-01-11 23:53:05.439 Transcoding /mnt/media/mythtv/mythtv-raw/2443_20091108103000.mpg done
> 	2010-01-11 23:53:05.494 mythtranscode: Error Renaming '/mnt/media/mythtv/mythtv-raw/2443_20091108103000.mpg.tmp' to '/mnt/media/mythtv/mythtv-raw/2443_20091108103000.nuv'
> 			eno: No such file or directory (2)
>
> Indeed the file is not there anymore though the entry is still fine in
> the mythconverg database.
>
> Admittedly I had started and stopped transcoding perhaps half a dozen
> times. Some in relatively rapid succession. I did this from 2
> different frontends (one is on the Linux backend server and the other
> is on a Windows laptop) and also from the mythweb interface. I also
> crashed the frontend a couple of times and restarted the mythbackend a
> couple of times during the transcoding interval -- but that is
> probably all a red herring.

If by, "red herring," you mean, "The type of unspecified procedure that 
results in a completely untested use case that /definitely/ caused the 
problem," I think you're exactly right.

There's no way to know from, "I did a bunch of things that weren't 
normal," exactly what went wrong.  My recommendation is to:

a) enable the mythtv-setup setting:

Save original files after transcoding (globally)
When set and the transcoder is active, the original files will be 
renamed to .old once the transcoding is complete.

b) make a backup copy of a recording (just in case)

c) do a transcode without all the circus tricks

and see if it works on your new system configuration.  If so, then 
unless you can find out which part of the procedure above caused the 
issue, it's probably not worth worrying about (because we can't fix an 
unidentified "bug").

My best guess is that you experienced a problem caused by a race 
condition caused by running multiple transcodes on the same recording at 
the same time--as the transcode jobs don't die when you shut down 
mythbackend.  So, the one that had the good transcoded file finished and 
cleaned up stuff--including stuff used by one of the other 
transcodes--and you lost the file.  This is pure guesswork, though, as I 
haven't even looked at the code (and don't plan to do so without 
something a little more specific pointing to a confirmed bug  :).

Mike


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