[mythtv-users] Where to dedicate processing power?

[Jim Minihane]

This arrangement I've suggested is more of a "proof of concept" for me. I
want to understand how the system can be "broken up". I have another thread
running asking about capturing DD5.1. One solution was an integrated SPDIF
input on the mobo. This would require 1 machine per tuner. It would probably
be the weakest machine(s) in the system. Don't worry about network. They'd
be in their own small network 10/100 or Gbit.
When it comes time to implement, I'd like to be able to add additional
tuners if I want to. The RAID will most likely be a 3Ware 9500S-12 or
9550S-12 card.
Here's my vision (bear with me)...
I have a 19" enclosed telecom/RF cabinet. I'd want 4+ DirectTV boxes
connected 4:1, 2:1, or even 1:1 with slave backends capturing S-Video and
DD5.1. They'd be managed by the Master backend with no tuners. The
RAID/storage would be in the master backend. Several TVs and a projector in
the house would be connected by their frontends to the master. If I wanted,
then I could add another machine to do commercial cutting.
Call me nuts, but this sounds pretty good. I don't mind spending the money
for hardware if I know it will all work when I hook it up. 1, 2, and 4U
servers are pretty cheap on ebay.

-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Anthony Vito
Sent: Tuesday, March 07, 2006 11:03 PM
To: Discussion about mythtv
Subject: Re: [mythtv-users] Where to dedicate processing power?

> Setup a RAID 5 array for recordings (since you'll have 4 tuners total
you'll
> want the speed),

This is a common misconception around here. A high bandwidth mpeg2
stream in SD is only 8 M(bits)ps or about .8 M(bytes)ps 4 of them are
a mezzly 3.2 M(bytes)ps. Most modern harddrives can sustain 60
M(bytes)ps. So there isn't much of an issue here. It 'can' become a
problem when a few tuners are writing and a few tuners are reading. (
I would like to find some numbers on how many writing tuners and
reading frontends it takes to max out a single disk. ) I Assume you
didn't mean a hardware RAID 5 solution, and RAID 5 in software will
give about about the same performance as RAID 1 on the read, and much
lower performance on the write.

Back to the OP. Since this lad doesn't have much CPU power to begin
with, I'd suggest a single large disk. If you wish for redundency and
couldn't bear to lose recordings in a crash, or if the single disk
does become a bottle neck, get another identical disk and build a RAID
1. This can be done non-destructively and at any point in the future.

Also, I agree with a previous suggestion to keep the Tuner cards all
in one place, and in the same machine as the drives. This will further
reduce CPU usage and network traffic.

--
Anthony Vito
anthony.vito at gmail.com
_______________________________________________
mythtv-users mailing list
mythtv-users at mythtv.org
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users