One of the things that we have had for a long time is a serial console server, which is to say a server that collects and logs serial console output from all of our regular servers (this is primarily Linux kernel messages, as we've moved away from making the serial port the 'real' kernel console). To date we've done this through actual serial ports on the servers, which we set up as an additional console. However, this has an obvious issue, which is that your servers need actual serial ports.

For a long time this was no problem; even basic 1U servers came with a serial port (often right besides the basic VGA video out; servers may be the last refuge of that particular connector). However, recently we discovered that we've received a mainstream server that doesn't have such a serial port, and it's not a basic 1U server either; it's the 24-bay SuperMicro hardware for our new (hardware) generation of fileservers. The only option for a serial console on this hardware will be Serial-over-LAN as part of its IPMI implementation.

(We've poked a bit at Serial over LAN before, but there have been a number of blockers, including that Linux only supports sending kernel messages to a single serial console so to date that's been the physical serial port.)

This is a switch that I've been vaguely expecting to happen for a while, but it's still sort of a surprise to see signs of it actually happening. The physical hardware for a serial port does add some cost and take up some space, and these days it can't be very heavily used, and IPMI has supported Serial over LAN for some time now. In a way it's surprising that serial ports on servers have lasted this long.

(Or perhaps server serial ports are more popular and heavily used in the industry than I expect. And certainly IPMI support has had problems in the past, when vendors often didn't give the BMC its own network port, which generally meant that you had to keep it off the network entirely.)

PS: This shift is potentially a good thing for us, since the hardware we use to implement our serial console server is increasingly old and I don't think equivalents are being made today. It's been very reliable so far, but sooner or later it's going to start failing.