[mythtvnz] Recording dropouts and disk performance...

[Rob Connolly]

On Sat, Feb 16, 2013 at 06:18:05PM +1300, Jean-Francois Pirus wrote:
> 
> Speed should never be an issue with current generation disks.
> 
> Check dmesg
> 
> SMART usually won't tell you anything until the drive is close to dead.
> 
> Run a SMART long test on each of the drives then you might see something in the SMART logs.
> 

Just re-checked dmesg and I still don't see anything, same in the other
log files. Perhaps I just don't know what I'm looking for (grepped for a
few things - ata, sd, ext, error, with the -i flag).

Running the SMART long test now. I had run it relatively recently
anyway, but we'll see if that turns up anything.

Investigating the problem further, it seems like this always occurs when
I have two recordings going simultaneously. In 2/3 cases these were back
to back recordings on the same channel since there is a 20 minute
overlap.

For reference this thread [0] describes the issue in more detail. I have
the exact same symptoms, recording starts and stops after a few minutes
with the aforementioned error. Myth reports that the recording was
sucessful and that the length and filesize are in the correct range,
but when downloading through mythweb a much smaller file is presented
(as expected from the error message).
There is also a post here [1] talking about RAID performance causing
this issue, I still need to look into that.

This afternoon I did some mysql performance tweaks with mysqltuner.pl
[2], so we'll see if that makes any difference.

Cheers,

Rob

[0] http://www.mythtv.org/pipermail/mythtv-users/2013-January/344956.html
[1] https://technpol.wordpress.com/category/technology-2/mythtv/
[2] https://github.com/rackerhacker/MySQLTuner-perl