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

[Jan Ceuleers]

On 29/06/15 18:06, Peter Bennett (cats22) wrote:
> 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.

Thanks Peter. I already have nobarrier active on my filesystems. This is
without risk since the backend's power is protected by a UPS.

The database resides on a RAID1 across 2 volumes (spinning rust), with a
third-one as hot spare. This RAID1 is actually partitioned: one
partition contains the root filesystem (which is where the database also
resides), another is /home.

The box has 4GB of RAM. I've been trying to upgrade but the motherboard
(Zotac H55-ITX) is very picky about which RAM it will work with and I
haven't yet been able to find 4GB sticks that work. Anyway: I don't
think that RAM starvation is an issue here; all expanding it would do is
add to the amount of cache since all applications put together need only
1.4GB, leaving 2.4GB for headroom and cache.

I know that mysql's memory usage can vary a lot based on the queries it
is executing at any one time, but I would expect mythfilldatabase not to
be the most memory-hungry task mythtv has mysql do (but rather the
scheduler).

I also know that mysql can need a lot of temporary storage; there is
more than 25GB of disk space available in the directory where it creates
its temporary files.

So anyway, this is why I was asking whether the interruption of
recordings was a known side effect of running mythfilldatabase. Seems it
isn't. I'll keep on the lookout for other causes.

Thanks to all who replied.

Jan