How to beat your last on premise server into submission
It's an unspoken rule of IT that when you might like a server to fail, it just keeps on running .... faithfully .... not missing a beat ... day after day after day.
This is the last server in your server room, nobody dare touch it because it does a critical something, it's done it for so many years and there's no documentation or staff member to say how it's special type of magic works.
As you move everything else, the cost to keep that last server there skyrockets as it becomes the only reason for air con, power, rack space, security, monitoring, backup and so on.
We can "lift and shift" or "rip and replace" that server with appropriate pre and post risk mitigations to protect against failure.
Strategies to move that stubborn server to the cloud
Chances are that it's not just the hardware and system software that's outdated. The application is probably an antique too. If there is an opportunity to redevelop the application or to adopt an off the shelf solution this might be your best bet.
2. Rip and Replace
If you cannot modernise the application, it may still be possible to modernise the server and operating system.
In this case you'd be able to host a new server in the cloud and run the legacy software on it.
You may need to do several successive upgrades with validation after each to fast track an upgrade path that ought to have been followed over the course of the server life, rather than at end of life.
3. Run an emulator
There are a number of techniques to wrap an old application so that it becomes compatible with a new server or to run the old application inside an emulator on an up to date server.
4. Lift and Shift
Some cloud hosting providers will allow your hardware in a private section of their rack space. As a last resort, that old server can be moved, however this is a stop gap solution and not a long term strategy.
5. Do Nothing
What got you to this point was a do nothing approach that saw this device not be proactively managed, to fall out of support and effectively to miss the window of opportunity for an upgrade path. You still have this option, it's just not a very good one!