[mythtv-users] MythTV Installer Usability: An Analysis

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

	Date: Fri, 04 Nov 2005 18:32:51 +1000
	From: ffrr <ffrr at tpg.com.au>

	Is this because the ringbuffer file seems to continually grow?  I have 
	noticed this.  Why does it do that? If you are not paused, surely the 
	file size should remain stable?

    Yes.  The ringbuffer grows monotonically -up to its configured limit-
    and then (I assume!) stops growing.  It's not clear to me why the
    installer defaults to a partition sufficient to hold 5.3 hours' worth
    for a 200GB disk, though; that seems like an awfully large buffer.

Hmm.  It belatedly occurs to me, of course, that the installer has no
way of knowing at the time it's partitioning the disk whether you're
planning on putting an HD card into the machine, either now or
sometime in the distant future, and an HD card might require quite
a bit of disk space to have even a moderate-duration buffer.
(This also makes the time-to-explode far shorter in this case.)

What -really- doesn't make sense to me, though, is why this thing
is in its own partition to start with.  Why not just put it in the
same partition that holds recordings?  Then it could trivially be
as large as the freespace on the disk, while not actually soaking
up space used for recordings if you'd rather use the space that
way (e.g., just dynamically adjust the ringbuffer to never exceed
the freespace on the device, plus maybe a margin so it can shrink
over time if the rest of the partition is filling up with recordings
from other tuners).  The current situation just wastes a lot of disk
space in order to be less flexible and more buggy.  (Is this specific
to KnoppMyth?  Having not (yet) rolled my own installation from a
different distro, it's difficult for me to tell.)

This is especially acute if one is setting up an MBE/SBE system,
as I am.  It's not clear to me at all how many ringbuffer partitions
there need to be---one for -each- machine in which some capture card
might be looking at live TV?  It's tempting to make only one, and
share it via NFS, but maybe I can live with one per machine just to
make the configuration easier and more robust.  I've also seen the
installer pick both 12GB and 5GB sizes for that buffer, and I have
no idea under what circumstances it decides; after so many reinstalls
in the past week, my memory on this is a bit hazy.