[mythtv-users] recording drive bottle neck suggestions..

[sonofzev at iinet.net.au]

Hi All 

On Sunday night I ended up having a bottle neck as it was the first time I ever
had 5 recordings going at one (1 HD 4 SD)... the system choked and I couldn't
watch as the recordings were going (although it appears the recordings ended up
fine).. The system couldn't seem to playback live TV or even a recording while it
was being recorded without major stuttering (F1 race so it was important!!)

The cpu seemed fine so I am assuming this is a bottle neck but it's only dual
core.. do I need more cores for this type of operation?

Ultimately I would like to be able to record 3 HD streams and 3 SD streams
simultaneously and playback 1 of those streams.. .. but that's just a wish.. not
a necessity.. 

My MBE recording drive is on an LVM partition on a 4-disk RAID 5 configuration...
With 300 GB set aside for recording... Itis on XFS with tuning for the RAID
configuration (large extensts and sunit and swidth)

I am about to migrate to a bigger case and will have enough room for at least 2
more drives.

Here are the options I see.

1. Add 2 more drives to the RAID 5 partition. This is my first preference as I am
hoping this will add enough bandwidth to record 5 shows.

2. Create a new RAID 0 for recording only removing the original 300GB partition
to utilise for extra space for transcoded videos. (will this be enough?)

3. Add 2 disks not in RAID and include them in the list of recording drives
deleting the original partition

4. Add 2 disks not in RAID and include them in the list of recording drives
keeping the original partition


I'd love your opinions on these or other potential options (that don't involve
dismantling the existing RAID)


Also, is XFS still worthwhile, or should I consider something like NILFS, btrfs
or ext4? 


I know that the simple answer is to restrict my tuners to record one channel at a
time but I have found recently that the multiple recordings per instance is good
especially with overlapping programs, now that it seems in Australia almost no
channel runs to schedule anymore.. 

cheers

ALlan