Sharing between 2 servers for storage.

I am quickly running out of space due to new signups I host with hostinger where the price is great, I have a KVM 8 server with them with 400gb of space,the biggest they do and none expandable on disk space. I keep reading a lot on here especially @Romulus posts and questions, Now I do not have much time left to make decissions I would like to stay with hostinger self hosted KVM8 as the price is great, I have a few KVM 8 servers with them one of them is empty , How can I use this for storage to daisy chain them just for hard drive usage purpose. Also I want to limit down time on the server while I do this .

I look forward to any response and guidance and thank you I appreciate your knowledge

Simon