With the End of Support for Windows Server 2008 on January 14th, 2020 - you no longer have the ability to receive Security Updates or Support for any servers running Windows Server 2008. If you need to keep these systems under some level of support after January 14th - you have a few limited options:
You can migrate your Server and workload up to Azure (Migrate to Azure Docs) and receive up to 3 free years of Security Updates and Support from Microsoft.
Provided you have an Enterprise Agreement / Volume License Agreement or you have purchased Software Assurance - you can enter into an Extended Support Agreement with Microsoft for up to 3 years and you will be able to register / enroll a fixed number of systems into this program.
Lets be honest - neither of these is a good LONG TERM strategy. Ultimately you need to migrate your workloads OFF of the old platform and on to a NEW platform (like Windows Server 2019). How do you go about doing that for key WORKLOADS that can't migrate up to the Cloud? I tracked down Ned Pyle, Principal Program Manager from the Windows Server Team to talk shop about the #1 Workload for servers: "The File Server".
Ned walks you through the Inventory / Transfer / Cutover phases of the Storage Migration Service - it's FREE with your license of Windows Server 2019. For a more detailed set of steps and procedures - check out https://aka.ms/WS2008Storage for complete documentation.