Sharing disk space between two Ubuntu hosts [closed]

Question

I have two Digital Ocean droplets (Ubuntu 14.04 LTS VPS instances):

• Alice: 40GB disk / 38GB used
• Bob: 20GB disk / 2GB used

Alice’s storage needs will continue to grow slowly but steadily. Rather than bumping Alice up to a more expensive image, is there an effective way of sharing some of Bob’s disk to Alice? I’m looking to transparently extending the filesystem rather than creating an additional partition if possible. Both droplets are hosted in the Digital Ocean nyc2 datacenter, both use a single ext4 partition, and they seem to have excellent connectivity between them.

Answer 1

Rather than bumping Alice up to a more expensive image, is there an effective way of sharing some of Bob's disk to Alice?

What you are talking about comes down to being so intricate—NFS mounts, etc…—that ultimately you might be better off growing Alice’s space to a more expensive image.

But part of the problem with the question is what exactly is eating up space? Actual application usage on the server? Files that need to be accessed immediately or archival items? Because you say:

I’m looking to transparently extending the filesystem rather than creating an additional partition if possible.

But honestly doing that transparently is not going to be easy. You need to better define—for us and for you—what’s eating up the space.

Perhaps something like Amazon S3 can help you offload your storage for the application running on the server itself.

But you need to provide more details since simply saying “more storage” does not address the issue.

EDIT: Based on the original poster’s comments this is about Bitcoin related files stored in .bitcoin/. The key thing you need to keep in mind is these are simply files store on a oath. So figure out where your .bitcoin/ directory is located, then see if you can adjust a config to change that path where they are stored. If you can change that path—which I am pretty confident yo can—then perhaps an NFS mount would work. Just setup an NFS mount, move the old block chain stuff to the new space, change the config to point to that new space & restart the process. But honestly you might be doing more work than it’s worth.

Answer 2

It depends on what you mean by "sharing", but some approaches

• NFS/SMB/sshfs: Bob will offer a directory of his file system where both can write/read to.
• iSCSI: Bob will offer a part of his space as a iSCSI block device. This can be used by Alice at will, e.g. as LVM PV, but not by Bob anymore (except Alice shares it back via NFS/SMB/sshfs).

Answer 3

Yes, there are ways to achieve something like this. But your question seems to indicate you're trying to circumvent the pricing structure of your VPS host. Questions asking about misusing services or equipment are inappropriate, just so you know.

You need to check with the policies of Digital Ocean and see what they allow. Just because you can do something doesn't mean you should do it. That being said, you may be able to use a network filesystem to get access to one instance's storage from another. Of course, that means you'll need to manage the different sized space allocations, but that's part of being an administrator. ;-)