[mythtvnz] Upgrade completed

[toby at np.co.nz]

I've finally finished my 'Ultimate' Myth setup after a lot of work and the
help of serveral people on this list with answers and recommendations.

I'd thought I'd share how the final setup looks..

Master Backend is a Dellpoweredge 2850, 2 x Dualcore Xeon 3.4Ghz with 4Gb
of RAM running 64bit Mythbuntu 10.04 + updates. 1 x 32Gb SCSI boot disk
(also with my music collection) and 5 x 72Gb SCSI disks each setup as a
seperate storage group. Video capture is through an HVR4000 which does both
DVB and Sky analog capture with a homemade serial IRBlaster. It might not
seem like a lot of storage, but for recordings that mostly auto expire, its
more than enough. Videos and DVD's are on a cheap linksys NAS box with a
couple of 1TB sata drives mounted via NFS.

It turned out to be reasonably straight forward getting the backend running
on the big 64bit box.  The HVR4000 just worked which I was very happy
about. The only difficulty was generating the 32bit diskless images from a
64bit backend, this required a bit of hacking and some deep googling to
make it all work, but now its going, updating the image is a breeze (and
takes < 10 seconds to compress).

The backend can record 5 programs at once and commflag them in realtime,
with an 8% total CPU load averaged across all 4 processors. Myth seems
smart enough to commflag the stream before it hits the disk so the IO on
the disks is negligble. I have mythcommflag capped at 4 simultaneous
processes and myth automatically allocates one commflag process to each of
the 4 processors. With that many storage groups, myth streams each
recording to its own disk and each commflag process is allocated its own
processor. Its nice to have enough horsepower available to do this and
still have responsive frontends. Running at full recording capacity the box
is barely idling and disk usage is an occasional flicker.

Frontend clients are Zotac Ion/Atom, HDMI output and network booting. I
can't recommend these boards enough as a frontend, they just worked out of
the box with practically no configuration required.

I have a 24Mbps 1km hi gain WIFI link to a 'second site' with a secondary
backend that has another dvb tuner. (we also share internet and telephone
over this link using asterisk so only one phone and internet connection
between the two sites). Video's music and TV recordings from both sites are
available on frontends at either site. The link works well and has more
than enough bandwidth for one client at both sites to be watching a program
recorded at the other site. We are using ubiquity bullet transponders which
I can't recommend enough. They are 'bulletproof', telco grade and cheap. We
took a lot of time to build proper antenna poles and the antenna alignment
process was painstakingly anal, but worth the effort for a very stable link.

I'm very happy with the final result, it feels totally bulletproof and
while the backend does have way more horsepower than is required, the
platform is rock solid and extremely responsive and on relfection
relatively cheap to put together. WAF is off the scale after years of
random crashes and flakiness on cobbled together hardware, everything
finally works the way it should do. I no longer go to watch a recording and
cross my fingers it worked or doesn't crash halfway through.

On reflection, for anyone contemplating building a myth system, I'd highly
recommend not cobbling a system together (other than for experimentation)
and buying the hardware to do it properly right from the start. Second hand
server grade hardware is significantly more powerful, stable and cheaper
than brand new consumer grade equipment and all the drivers just work out
of the box. The Dell 2850 also has the DRAC module installed, so I can VNC
into the server remotely and watch it boot or turn it off or on and the VNC
process is running on its own hardware so does not load down the box in any
way.

Cheers
Toby


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