[mythtv-users] Slightly OT: Powering up remotely

Christopher Sean Hilton chris at vindaloo.com
Wed Sep 23 02:25:37 UTC 2020

On Tue, Sep 22, 2020 at 12:15:19PM -0400, Ian Evans wrote:
> ============================================================
> On Mon, Sep 21, 2020 at 7:02 PM jam at tigger.ws <jam at tigger.ws> wrote:
>     > On 22 Sep 2020, at 2:13 am, Ian Evans <dheianevans at gmail.com> wrote:
>     >
>     > 1) Let's say it auto-started but is currently sitting there
>     >    with some "press y to continue" drive/os message. To future
>     >    proof this, aren't there some motherboards that allow you
>     >    to have remote KVM access through the bios?
>     There are grub kernel settings
>     fsck=force fsck=repair
>     The logic being either the disk is trashed and saying y or n
>     during fsck wont help you, or saying y will fix your disk. In
>     any event (no spinning rust) I do noy find fsck obtrusive. Im
>     using EXT4

I'm curious to see what this is when you get back to investigate. In
my experience it could be something very simple. In my recent
experience it wasn't but that's another story. The sequence of events
to restore power for systems held can be more complicated than it
would seem. Failures in the process could lead to a remote machine
being in a safe completely off state.

Three things might help you here:

- A remote switchable AC power unit
- A Serial Console on your MythTV and a "terminal server"

If you had either IPMI or a Serial console and a remote switchable
plug for your MythTV server, you would have some options. IPMI is what
you are talking about. It lets you get into your server before the
operating system boots up. A remote switchable power plug would let
you turn the server off and on from a remote location. Assuming the
BIOS is setup to automatically turn the power on after a power cut,
that should boot the server. A serial console and a terminal server
from which to access it would allow you to control the server after
the operation system boots even if it gets stuck before being able to
go multi-user. If your server has a serial console which
you can access remotely, you can use the serial console to answer the
fsck questions and possibly fix the filesystem and then transition
back to running.

Without going into great detail, there are plenty of remote switchable
AC plugs that you can find. So long as you can figure out a way to
remotely access it from the internet, that would help. Best here would
be something like an APC AP7900 Switchable PDU. You can get those on
eBay for between US $50 and $120. I'm assuming that you are in the US
here. I don't know what they would go for on the other side of the

As for serial consoles, they should be possible in Linux. My rough
guess as to cost is again about $100. This sounds expensive but you
need both a serial console and another server from which you access
the console. My $100 estimate:

- puts a PCIe serial card in your MythTV;

- purchases a Raspberry Pi and the other dedicated hardware that you
  need to access the MythTV console.

The basic operation would then be to use ssh into the raspberry
pi; then use a serial access program like `cu` to jump from the pi's
ssh command line to the serial console.

In summary, there's no way to know what the right solution is until
you get back home because right now you don't know enough about how
the system failed.


      __o          "All I was trying to do was get home from work."
    _`\<,_           -Rosa Parks
Christopher Sean Hilton                    [chris/at/vindaloo/dot/com]

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