Hi everyone!

So I run the Bitcoin Core full node software on my PC and keep my btc there.  My PC has a 512gb SSD (c:\) as my main drive and a 2TB backup hard drive (d:\), which is where my Bitcoin Core program stores everything.  The 2TB drive is about 4 years old and is almost full - I'm about to replace it with a 4tb hard drive and need to backup everything. 

What's the best way to achieve this?  I remember my pass phrase but I don't remember writing down any keys or words, or anything like that.  it's been years since I originally installed it.