How to combine multiple HDDs into one big HDD in Linux?

Question

I'm very new to Linux, being mainly a Windows 7 user, so I may not understand Linux-specific commands without explanation.

I've decided to build a NAS running some form of Linux (probably FreeBSD or even FreeNAS) with SnapRAID for redundancy.

I currently have about ten 1TB and 2TB external drives, which I intend to take out of their enclosures and mount as normal HDDs via SATA. Most of these drives contain a large amount of data.

My question is this: Is it possible to "combine" the drives such that they appear to the OS and all programs to be a single logical drive (of around 13-14TB) without deleting the data? I assume this would be completed with LVM, but before I go spending a lot of money on NAS hardware I want to make sure this will work.

Solution

I figured it out myself! I discovered mhddfs and it seems to do exactly what I want.

I'm about to test with a VirtualBox, but I believe I will be using SnapRAID with mhddfs (probably all running on Lubuntu) and it solves my problem.

Comments

[Clonkex]

The issue is that we have no backups (hence this attempt to combine the drives with software RAID, to give us some redundancy) and no space to move data (well - maybe we can manage that, but if possible we'd prefer not to). I read something about logical volume groups - would that achieve what I need?

[Clonkex]

Mount points (as you say) are always an option, but also something we'd prefer to avoid if possible.

[Clonkex]

I'm looking into UnionFS right now, so I'll get back to you with that. To clarify, what we need to be able to do is have large files split across the drives if they can't fit in the remaining space on the physical drive.

[Clonkex]

As far as I can tell, UnionFS doesn't do what we want. Yes it virtually merges the directory structures, but it doesn't combine the drives. Unless someone can provide a better answer, formatting and partitioning the disks one at a time is looking more and more necessary (*sadface*).

[Clonkex]

Yes, that is correct, I wanted to combine the physical drives into one giant virtual drive, but... I've already achieved this, and I never said anything about RAID-0. I suppose your answer may help others at some point, though...

[CBenni]

I tried it under ubuntu and it seems to work perfectly as well. Thank you!

[Clonkex]

@CBenni Glad to hear! We used it for many months without issue before we eventually decided to switch to Windows for other reasons (mostly compatibility with game servers and the like). On Windows we paid for Drive Bender, which does basically the same thing. Slightly dodgy interface but has worked perfectly for the past year or so.