[mythtv-users] Running mythbackend on a low-power device

Tortise tortise at paradise.net.nz
Fri Nov 30 00:33:47 UTC 2012

Is the USB on a R pi a bottleneck?  If its a 480 usb 2 interface, suggests
to me the 100 nic is more likely to be the constricter - or seems likely to
be the deeper architecture? Im still waiting for mine to test this....
Anyone tested this?

I've been considering using a Rpi master backend, that connects with a
hdhomerun (or two?) and some sort of inevitably noisy multi hdd multi TB
machine out of ear shot in a utility space, preferably with demand power
control on that machine.

A significant concern expressed previously is that the scheduler is a
significant run job that may be too big for the pis cpu to handle, which I
think is about the equivalent of a pentium 400 (?).  It seems if a
sheevaplug can run the scheduler then a pi should be able to also(?).

A more concerning question for me is what will the simultaneous recording /
playback capacity be, having a system working that has effectively had no
discernable limits (where 8 hd programs can be simultaneously recorded with
seamless recording playback co-existing (using 2 x 500 pci cards) = +++
kudos to the devs!) seems a level of performance that a rpi will be
challenged to approach where the single LAN pipe will be at least part of
the constraints explanation...
 On Nov 30, 2012 7:22 AM, "Tyler T" <tylernt at gmail.com> wrote:

> I use a SheevaPlug for my Myth BE. I can record two HD shows from my
> HDHomeRun, not sure about 3 (I do have multirec enabled, so maybe I
> have... never checked).
> The thing about the Pi is the USB bottleneck for disk I/O. Worse, the
> Pi's network adapter is also routed through USB internally. CPU
> shouldn't be a problem, and RAM shouldn't be a problem (especially
> with the new 512MB Pi), but disk AND network I/O being shoveled
> through one USB host controller would probably choke.
> The Pi aside, some other ARM device (NAS or Sheeva) with eSATA/SATA*
> ought to have the I/O grunt you need for a BE. The Pi could still be a
> separate FE, albeit running XBMC since Myth doesn't support the Pi's
> OpenMAX video acceleration yet.
> * Not all Sheeva and cousins have SATA, check the specs to be sure.
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