[mythtv-users] Massive HDD activity at show starts

[Jan Schneider]

Zitat von Mark Kendall <mark.kendall at gmail.com>:

> On 3 June 2010 17:17, Jan Schneider <jan at horde.org> wrote:
>> Hi,
>>
>> I'm experiencing something in 23-fixes that didn't happen with 22-fixes and
>> seems to be worse when wathing HD channels:
>> if watching LiveTV, when one shows ends and the next one starts, there is so
>> much (audible) HDD activity (i.e. probably seek operations), that a lot of
>> frames are dropped (from current LiveTV as well as recordings that happen at
>> the same time). Sometimes up to one or two seconds are missing. In the worst
>> case the FE is so much off the track, that I have constant audio pauses
>> until I restart LiveTV.
>>
>> This is a combined BE/FE with XFS for recordings and ext3 for anything else.
>>
>> I'm wondering:
>> - What is causing this much activity? There should be just 2 or 3 DB INSERTs
>> beside the regular recording activities, right?
>> - Why is this happening now?
>> - How can fix this, or at least track the cause further down?
>
> 3 possible causes come to mind:-
>
> - Preview generation. I've been trying to track down some problems
> with the frontend spawning multiple preview generation threads in
> trunk - it could well be occurring in 0.23-fixes as well. When you
> 'switch' to the new show, preview generation may be initiated for the
> show that's just finished.
>
> - Expiry of old recordings. This is more likely to happen with actual
> channel changes and channel surfing, but I often see the backend
> cleaning up short live tv clips after a channel change and this can
> cause hiccups in the frontend.
>
> - Switching to the new 'live tv recording'. The live tv switch code
> could do with some love and it isn't always very graceful.
>
> The easiest way to start tracking it down is to generate some logs
> from the frontend and backend with -v playback logging.

Thanks! If the other suggestions from this thread don't work, this  
will help me to find a starting point for tracking it down.

Jan.

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