I have a lot of data at home and a difficult backup scheme.
On my Linux box I have 8 external hard disks attached for a total of 11T of data. Music, video, photos, documents, odds and ends. They aren't on all the time. I turn them on, transfer data to them, sync the data, then turn them off. I've been doing this for years, and upgrading hard disks every few years. I started with 500 gig, then 1T, 2T and now I have some 3T.
On my Mac, I have a similar arrangement. What's on my Linux external hard disks is kept in sync with the hard disks on my Mac. They are my backup.
This is not a satisfactory arrangement. I've been looking for a solution and finally took Doug's advice and bought a Drobo. Doug has had one for years. Adorama, a camera shop, were having a sale last week and I got an empty Drobo for $229. I got the plain 4-bay Drobo that attaches via USB3 to a desktop. I did not get the standalone network version.
It arrived today and I got a chance to play with it. First thing that was cute was that the Drobo was packed inside a neat fabric tote bag.
A Drobo is a storage device. This one has four bays. You can put four hard disks in it, each up to 4T. They do not all have to be the same, you can mix and match drives and makes and models. They recommend that they all be the same speed, but other than that there is no restriction. It will mount them in a RAID array. How the RAID works depends on how many disks you have in it, the sizes of them, and one setting. If you have all four bays populated, then you can decide whether you can tolerate one disk failing, or two disks failing. If you tolerate two, then you get less storage.
I had two brand new 500G drives sitting around so I put them in and fired it up just to test it. I attached it to my Mac Mini, downloaded and installed the Dashboard software from Drobo, and let it run. There are Mac and Windows clients. I read that there is a Linux client that will run an ext3 partition, but I didn't experiment with that.
When the Dashboard found the Drobo it asked if I wanted to initialise the drives. I did. As it was Mac, the only choice was HFS+. It created a 16T partition, but I'm not sure why. The website says the current maximum in my Drobo is 32T. But anyway, it set up a 16T partition. Even if I fully populate it, I will never get 16T. It's RAID, so I will get about 10.8 T of usable space.
It initialised my two little drives, and I had 464 G of usable space.
The front panel slips on and off magnetically. You can see indicator lights beside each used bay. Solid blue - all is good. Red - not so good. The unit is solid and heavy, feels very well engineered. The weight will help dampen any vibration. It looks like it will be a very good solution.
It isn't much use yet. I am going to populate it with 4 3T drives. That will give me 8T of usable space. Clearly, I will not fit all my current data. I need to clean up what I have anyway. I have too much junk.
The 3T drives are about $120. When the 4T hit that price, I will upgrade the drives. You can remove one drive and replace it with a larger size and it will automatically fold it in and upgrade the data. So it's easy to upgrade all 3T to all 4T, just takes some time. The Drobo has got some really neat features like this. If you want to see how the space works, the Drobo website has a really neat graphical capacity calculator.
I do not plan on putting SSDs in it. A 3T disk drive costs about $120. An SSD with 3T costs several thousand dollars. RAID used to mean a Redundant Array of Inexpensive Drives. SSDs are not inexpensive in the sizes I am looking at to fit my data.