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Comment by paranoidrobot | Hacker News Reader

Interesting solution.

I wonder if you could make the 'wake up' a bit more advanced.

Run tcpdump or something similar on the Pi, with a filter set for inbound packets to the media server on ports that Plex or Time Machine uses. If it sees those packets, send the WoL magic packet.

This might not work if your switch does proper port isolation - but you could perhaps add port mirroring or something like that.

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Perhaps using something like keepalived on your server and Pi could be useful here. When the server is off the ip will failover to the Pi to receive server traffic to know when to power on the server. Once the request comes in and the pi powers on the server, it'll come active again and recieve the IP while the pi goes in to standby. That way the Pi doesnt need to be in the read or write path.

keepalived seems like a great idea.

I'm not sure how Plex clients would handle it, but putting an nginx server with the same certificates and just returning HTTP 429 (Too Fast) or 500's and a "Please try again in 1 minute" response, along with sending the magic packet would work great for most HTTP based things.

I think you could maybe just snoop for ARP - when you see something trying to discover the IP wake the machine up. Supposedly some Intel NICs [0] already support this, though they also wake on multicast which you wouldn't want here.

[0] https://forums.unraid.net/topic/6455-how-to-wake-on-arp-unra...

Thinking of Icinga or other monitoring tools, they would trigger such a request everytime.

Reverse proxy on the Pi? If a request comes in for the server and x minutes have elapsed since last activity/WoL, send a new WoL.

I'm a little out of my wheelhouse though. Maybe that would only work for HTTP which will not cover Time Machine?

Does Time Machine run on a schedule? Add a cron job (whatever the Mac equivalent is) to send a WoL ~1min beforehand?

>Does Time Machine run on a schedule? Add a cron job (whatever the Mac equivalent is) to send a WoL ~1min beforehand?

I believe on x86 the BIOS supports setting a timer for self-wakeup. The OS can tell the BIOS "I'm going to sleep. Pull me out of sleep if the RTC passes this datetime."

Of all the x86 type BIOS and EFI, I've never seen one that didn't support that. Even thinclients and things you'd expect to leave that feature out.

I see BIOS not supporting it back in the 90's

Reverse proxy means that your pi now has to handle all the traffic for Plex and any other services. It could also make other things difficult like CIFS/whatever else you're hosting.

Depending on what Pi you're using, it's networking is over USB, and so is quite performance constrained.

Maybe use local DNS with a very low TTL. Send WOL on DNS request.

If we're talking about Plex, then local DNS is probably not going to help.

The traffic could be coming in via your WAN connection and your router is just going to forward it to an IP.

You could use DSR (Direct Server Return) so that the pi only handles the initial connection. All the video traffic goes directly from the server to you without passing through the pi.

Pi is perfectly capable of running Plex. Maybe run it on there with some cached data on the Pi and then the main content stored on the server. Then when accessing Plex, it will have all of the content showing what is available but in the background will be starting up the main server with the main content.

I guess you could just attach an external HDD to the Pi. Thats worked for me before.

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