Simplest solution is to enable bitcoind pruning (which is limiting number of blocks to certain value, basically discarding old blocks, so hard drive don't overspill). But Futurebit has not got around to support their users properly - this is nowhere to be found in the settings. They knew the day is coming but did nothing, now all early batch users with 512GB drives running with crashed bitcoin nodes, not providing any benefit to Bitcoin blockchain p2p network, which was heavily advertised during sales.
You are left out, you either have to configure pruning yourself in bitcoind config files inside Apollo, or purchase 1TB NVMe drive, brand new for around 70 USD (in the UK where I live) last time I checked.
So I:
1. Swap the internal drive, which is more annoyance than I'd prefer to deal with..
2. Attempt to modify the software, which is more annoyance than I'd prefer to deal with..
or
3. Ignore the situation and lose out on the money and purpose for buying a node unit to begin with?
Yes, exactly, that's all options you have. As Sledge0001 mentioned, buying new 1TB NVMe drive may be easiest option, but it costs money. Second great alternative option would be Futurebit adding pruning, so you can lose out 20GB of old blocks and still serve 490GB of newer blocks. This interferes with planned in the future Lightning Node support, but LN support is nowhere at the moment.
But unfortunately, because Futurebit did nothing to prevent this, we now arrived at option no. 3, where ALL nodes from 512GB users just crashed and no one is serving any blocks to Bitcoin network, and no one (apart from few here in this thread) even knows why, because there was no announcement or warning to users, no newsletter, mailing, nothing. Every node just dead.
Edit: Before someone mentions this issue, to my knowledge pruned node are seeding blocks, and they are considered as "full nodes": https://bitcoin.stackexchange.com/questions/72617/how-can-a-pruned-node-be-classed-a-full-node-without-the-full-blockchain says:
Amused. Just got an email from FutureBit perfectly explaining how to upgrade the drive.
At your own cost, of course. No pruning in sight.
And I received no e-mail whatsoever, so I assume it was you who contacted them, and another thousand of users get nothing.