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Re: Using serial console as a poor mans IP kvm?



On Thu, Sep 08, 2016 at 10:26:59PM +0300, Jarle Aase wrote:
> I want to set up a few servers at home. Unfortunately, as I live in Bulgaria
> at the moment, the electric power is gone pretty often for longer periods
> than my UPS'es can deal with. So my servers will have to be started at least
> a few times every quarter.
> 
> Another challenge with living in Bulgaria is that there is no law or order.
> The Police is just a branch of the Mafia. I need to protect the data on the
> servers with full disk encryption in case they are stolen.
> 
> That means that I need to reboot the servers relatively often, and provide
> the luks passwords every time. Some times I am far away when this happens. I
> have been considering Supermicro motherboards with built in support for
> remote management - or old KVM IP switches from Ebay. The problem with
> Supermicro is that it's expensive and difficult to get the RAM required for
> their recent Skylake boards. The problem with Ebay is that few suppliers
> ships to Bulgaria, and getting anything trough the custom's here takes a
> whole day. Then there is the question if the device works at all...
> 
> So I'm thinking about serial consoles. My gateway router will reboot after
> an outage, and it can act as a VPN endpoint. So I can access IP devices.
> With a rasberry pi and some relays, I can probably trigger a cold reboot
> whenever I need to. If I could log on to the grub console on the servers
> over a serial link, that's all I need, really.
> 
> Does anyone here have any experience with remote control with Debian boxes
> over serial? Will it work reliable?

We use serial consoles on Debian and Oracle Linux boxes all the
time, and have done so for more than a decade. They are more
dependable than anything else -- once you have set them up and
tested them through a full reboot cycle.

There are relatively expensive, but compact, devices that will
do both serial access and power switching. 8 of each is a common
configuration, as is 16. We like WTI boxes.

I am somewhat suspicious of USB-to-serial adapters in general,
but they are cheap and you can hook up lots at once through a
USB hub. You will probably want to test several brands in order
to find something reliable.

Incidentally, there are very few applications in which a Skylake
processor will be notably faster than the previous generation of 
Broadwells -- and Broadwells can use DDR3. You might save a lot 
of money and get built-in KVMs that way.

-dsr-


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