MythTV storage

[blu at vl.com (Tom Metro)]

Robert La Ferla wrote:
> Tom Metro wrote:
>> ...pair of 320 GB drives in a software RAID 1 set...
> 
> Wow.  What did you record that took up nearly 640GB?

As noted, that was a RAID 1 set, so it was "only" 320 GB of total 
capacity. That aside, the reason why it used up space so quickly was 
that the "out-of-the-box" defaults for MythTV is to use about 2 GB per 
hour of video:

http://www.mythtv.org/wiki/index.php/Recording_Parameters

(480 x 480 resolution at an average bit rate of 4.5 Mbps) This default 
setting seems a bit overkill to me for standard def., so as soon as I 
read up on these settings I made adjustments that should drop usage in half.

I had originally planned out the capacity with the assumption that I'd 
be transcoding the video to Xvid (MPEG4), which takes up about 1/6th the 
space, but then I learned that the front-end I planned to use, a 
Hauppauge MediaMVP, is limited to MPEG2 playback. (It has hardware for 
that, and lacks the horsepower to do MPEG4 in software.) There are 
workarounds, such playing the video on a back-end machine with more 
horsepower and using the MediaMVP as a VNC client, or using a VLC server 
that transcodes the video to MPEG2 in real time, but I haven't had a 
chance to play with those options, so for now I'm sticking with the less 
space efficient MPEG2.


> ...I just picked up a couple of 500GB SATA drives for a audio/video
> jukebox server. What RAID configuration would you use? If I were to buy
> a 3rd drive, what RAID configuration would you use?

Assuming your goal is fault tolerance, with two drives your choices are 
fairly limited (RAID 1), unless you split up each drive into multiple 
partitions and combine those in a RAID 5 set (which I think is doable 
with software RAID). With 3 drives, RAID 5 should give you the most space.

  -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/

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