[mythtv-users] Can mythfilldatabase interrupt recordings in progress?

[Peter Bennett (cats22)]

On 06/29/2015 03:02 AM, Jan Ceuleers wrote:
> Dear list,
>
> Due to where I'm based (Belgium) I need to grab metadata from multiple
> sources. Furthermore I have two video sources which have overlapping
> channels. In order to deal with all of this I run a nightly script that
> runs all of the metadata grabbers followed by mythfilldatabase --file
> (multiple times).
>
> Very occasionally I see interrupted recordings and I suspect that this
> might be due to mythfilldatabase being run while a recording is in
> progress. When this happens I end up with two files for the same
> recording: the second starts where the first ended (with a few seconds
> missing in between).
>
> Is this possible/plausible? Because if it is I need to detect the
> backend's status and defer the mythfilldatabase runs until after any
> recordings have finished.
>
> Otherwise I need to look for other causes (such as backend restarts; I
> know that these would produce the symptoms I'm seeing but I already only
> do that when no recordings are in progress).
>
> Thanks, Jan
>
With ext4 file system the mysql database can cause excessive thrashing
when running mythfilldatabase. You can actually hear the disk grinding.
My solution to this is to update the /etc/fstab to include the nobarrier
parameter on the file system that has the mysql database. This resolves
the problem and makes the run of mythfilldatabase much quicker. This may
present some risk of data corruption during a power failure. My
/etc/fstab line is as follows

UUID=900c3f88-ce0c-4a92-8e28-9ac04fdd1b09 /               ext4   
nobarrier,errors=remount-ro 0       1

Peter