[mythtv-users] truncated recording

[George Mari]

On 2/17/14, 8:40 PM, Mark Wedel wrote:
> On 02/17/14 03:30 AM, Mike Perkins wrote:
>> On 17/02/14 02:45, Mark Wedel wrote:
>>>
>>>   A few nights ago, my recording of OTA olympic recording was 
>>> truncated.  It
>>> would end after about 15 minutes.
>>>
>>>   Since I started watching it while it was still on, mythtv was 
>>> claiming the
>>> space used was increasing, and after it finished recording, 
>>> statedthe recorded
>>> size was about 25 GB.
>>>
>>>   However, using the info to find out the file name, and then 
>>> finding the actual
>>> file in the filesystem, it was about 1 GB.  Mythtv itself did not 
>>> state any
>>> errors with the recording.
>>>
[deleted]
>  There are no errors in the log messages or anything else to indicate 
> a disk problem, though that isn't to say that might not be the cause.
>
>  But in that case, I would expect that mythtv would see an error 
> writing the data out, and thus not presume the file was recorded OK.  
> Mythtv clearly believed it was writing out data, yet the file itself 
> does not reflect that.
[deleted]

I know you said you didn't find any errors in the log files, but this 
sounds exactly like the problem I've been trying to resolve on my system 
the last couple of weeks.  In my case it's not exactly a disk problem, 
but a disk system performance problem.  It's very clearly spelled out in 
the error messages stored in the logs - I usually get several of these 
messages:

Feb  9 03:26:26 poseidon mythbackend[2644]: 2014-02-09 03:26:26.416829 W 
TFW(/video/recordings/2051_20140209060000.mpg:83): write(65424) cnt 63 
total 3851744 -- took a long time, 2936 ms
Feb  9 03:26:31 poseidon mythbackend[2644]: 2014-02-09 03:26:31.448490 W 
TFW(/video/recordings/2051_20140209060000.mpg:83): write(12408) cnt 45 
total 2815864 -- took a long time, 1484 ms
Feb  9 03:26:42 poseidon mythbackend[2644]: 2014-02-09 03:26:42.383568 W 
TFW(/video/recordings/2051_20140209060000.mpg:83): write(46248) cnt 80 
total 4935940 -- took a long time, 2503 ms

...followed by this:

Feb 11 23:06:36 poseidon mythbackend: 2014-02-11 23:06:36.478976 E 
TFW(/video/recordings/2021_20140212043500.mpg:75): Maximum buffer size 
exceeded.
Feb 11 23:06:36 poseidon mythbackend: file will be truncated, no further 
writing will be done.
Feb 11 23:06:36 poseidon mythbackend: This generally indicates your disk 
performance
Feb 11 23:06:36 poseidon mythbackend: is insufficient to deal with the 
number of on-going
Feb 11 23:06:36 poseidon mythbackend: recordings, or you have a disk 
failure.

Sounds like the exact symptoms you're seeing - file is truncated, and 
shows much larger size on in the MythFrontend UI than what is actually 
on the disk.  I have 4 ATSC tuners recording to a single, 4-disk RAID5 
array, and have recently done some tuning of the array and disks to 
pretty much eliminate the problem when multiple tuners are recording.

Is it possible your mythbackend messages are being logged somewhere 
other than where you are looking?