[mythtv-users] MythTV 0.23 backend suddenly auto-expired a ton of recordings...

[f-myth-users at media.mit.edu]

This has probably been proposed as a feature request before, but I
can't find it.  I never use the autoexpirer, in part because I've
never trusted it.  And I've never trusted it precisely because some
transient error (like an unmounted or improperly-mounted filesystem)
might cause it to expire -everything-, essentially instantly.

I would trust it more (and perhaps Brett's recent disaster might have
been mostly avoided) if there was a way for users to say, "Never expire
more than this many recordings in a 24-hour period."  Yes, it's another
knob to tweak, and Myth is trying to get rid of knobs.

But accidents happen.  Things like this are precisely why rsync, for
example, has a --max-delete arg.

And whether it's an accident or a hard-to-trigger bug, it's a -much-
softer error if Myth fails to record something new because it ran out
of space than if it expires every single recording.  In the former
case, you'll notice, perhaps be able to get a repeat, and bump up the
limits.  In the latter, you're completely screwed.  -And- you probably
can't debug it because it's too late to turn on the debugging.  Or,
you know full well why it happened (because, say, you typoed a space
limit, or misunderstood which filesystems it applied to), but there's
no way to -check- your new settings before Myth goes and blows away
everything.  That's a hard way to learn you've mis-set something.

If this setting already exists and I don't know about it, great.  But
I'll bet it's set to "delete without limit" by default if so, and
that's not so great...

[Special bonus:  if it hits the limit per day, -tell the user- somehow
so he discovers something's wrong!  By definition, it shouldn't hit
this, so telling the user ASAP is far kinder than hoping he notices
that his recordings are being eaten away, and far faster than he had
anticipated they might...  Even better, whenever the setting is
changed, instantly evaluate the state of all SG"s and say, "The
current setting will immediately expire N recordings to free G
gigabytes in the following SG's.  Okay to proceed?"  That should
at least stop a fumble-finger or misunderstanding from blowing away
large quanities of stuff immediately, though it won't help if the
filesystem does something strange.]

It's also weird that, judging by some recent reports I've seen, it
seems to expire things in such a random order.  (I seem to recall
another relatively-recent "it expired everything" bug report, again
saying things went in a random order, but I can't find that, either;
the most-recent example was a spider hitting someone's mythweb---not
the expirer at all---and I'm definitely not thinking of that one.)