Restoring old r270 mining rig

[rarecoil]

This is an excellent idea! I happen to have a 250GB ssd lying around - I'll hook it up to 10TB HGST and away go my issues.

I'm not sure what's supported on ancient Ubuntu, but you can make an SSD-cached HDD (aka "SSHD") from two drives using bcache: https://wiki.archlinux.org/index.php/Bcache

This way you do not need to handle migration between slow and fast storage; you can just cache on the SSD transparently.