[mythtv-users] Immediate autoexpire recent rec. despite plenty of old rec. to expire

[John Pilkington]

On 30/10/13 09:48, warpme wrote:
> Hi *
>
> I need small consultancy regarding unpleasant issue witch started
> recently in my production system: random recent recordings are quickly
> 'disappearing' causing users complain like 'argh my favorite show again
> wasn't recorded'.
>
> Checking on logs it looks like those recording were recorded OK - but
> they expired immediately (within minutes after rec. finishes).
> My hypothesis is that myth expiring them for making room for new
> recordings. But in the same time few weeks old recordings are not expired...
> It was surprise for me as on 6T Default SG I have 2T space which is
> "Used by Auto-expirable Recordings" - so theoretically old. recordings
> from this pool should be used first for making room for new recordings.
>
> My 6T Default SG is sum of 2 volumes: 2T partition used since initial
> system build (/mythtv/tv) and 4T drive (/myth/tv1) added half Year ago
> as storage expansion.
> StorageScheduler is "Combination".
> Looking on few 'too quickly' expired recordings - they always were on
> '/mythtv/tv' (old drive).
>
> Now I see potential root cause: if 'old drive' is almost full with
> non-expirable recordings - then if scheduler schedules multiple new rec
> (my wife can schedule 4-7 concurrent on prime time) - some of them will
> be assigned to this drive and will cause expiration of other, recent
> recordings despite other drive (/myth/tv1) had candidates 1-month old
> rec. to expire. This is just theory.
>
> To verify this hypothesis will be good to count space occupied by
> non-expirable recordings per SG member ( '/mythtv/tv' here).
> Is there easy way to do this?
>
> Generally, looking on this issue from overall perspective: potentially I
> see where I do mistake: I assume SG is nice way to expand storage when
> user has lack of space.
> I was happy not going with things like LVM (as member failure brings
> whole volume down).
>
> Hypothesis from beginning of this post (if verified as correct one)
> shows that SG is perfect for IO scaling - but not for space scaling.
> I suspect only proper solution of my issue is moving from application
> level striping (mythtv SG) to fs level striping (LVM) or mass storage
> level striping (RAID)...
> Unfortunately this is quite difficult to do me as I don't have 6T temp
> storage needed for such conversion.
>
> Do anybody see other solution here?
>

It sounds as if you have a problem with the storage group disk 
scheduler, on around page 3 of the General menu in mythtvsetup.  I know 
I lost some recordings when I changed from 'Balanced free space' 
recently after, IIRC, Mike Dean had said that that one had a bug.  For 
me the alternatives seemed worse, and I went back.  I can't really 
investigate further without disrupting things, but that's what I would 
check.  Of course, I don't know why you are suddenly seeing this.

John P