[mythtv-users] Strange Issue with Myth and HDHomeRun

Billy Macdonald billymacdonald at gmail.com
Wed Feb 14 16:32:26 UTC 2007

On 2/13/07, f-myth-users at media.mit.edu <f-myth-users at media.mit.edu> wrote:
> Where exactly is your database?
> As a PVR-x50 user who's been getting screwed for a year by glitches
> caused by MySQL locking winding up locking out other table accesses,
> this is a sore spot.
> I'm assuming that the HDHR isn't trying to write into recordedmarkup
> or its SVN incarnation (unlike the ivtv-based encoders), but I'm
> wondering if perhaps there's something wrong with your database
> (like crashed or extremely un-optimized tables) that's either causing
> outright disk contention, or lots of swapping that is itself screwing
> your ability to write to disk.  So you might try repairing and
> optimizing tables (if you don't already) and see if that helps.
> And of course the FE makes large transient demands on the database,
> hence my suspicion.  Is your DB on the master backend's CPU?  Same
> disk, or a different disk?  (In -my- case, of course, it made no
> difference, since it was the DB locking itself that was a problem and
> not contention for disk bandwidth, but this wasn't obvious for most of
> a year.)  Is your backend swapping a lot?  Can you try moving your
> database to a completely different machine to run a test?
> (You can accomplish this latter, essentially, by shutting down MySQL,
> copying its files to some other machine -with a compatible version-
> installed [don't recklessly switch MySQL versions if you're just
> copying raw database files w/o import/export!], and changing the
> config file on your backend to point to whichever host now has the DB.)
> P.S.  If your test system is using the MySQL server on your production
> backend, of course, you're splitting things off in a way that might
> cause the test system to work fine while the production machine is
> encountering contention issues...

The HDHR drivers do the same updating to recorded as the IVTV recorder
code and I get the same glitches on my hdhr recordings as I do on my
pvr250 recordings.  Actually, the glitches are worse on the HDHR
recordings because of the higher bitrate, more is lost when the buffer
overflows.   Not a slight to HDHR btw, I love it.

These issues appear is momentary glitches.  John's appear as long
drawn out glitches.  I don't think the sql locking is John's issue.

When I implemented my HDHR recorders I had to update switch and NIC to
gigabit.  I have two units, so four possible simultaneous recordings.
I didn't follow the whole thread, but a quick skim makes it sound like
network has been ruled out.

Has anyone verified that the NICs are in full duplex/100 when
connected to a switch on the B/E?

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