Should I bother with small drives?

I bought my Drobo over 6 months ago. To get me started, I just bought two 1TB drives. I churned happily along for a few weeks. Then when I was cleaning out some of my old computer equipment, I found a 100GB SATA drive I had long replaced in my PC with a 500GB. I figured, rather than let it collect dust in the closet, I’d pop it into my Drobo. I was happy to see I now have almost a full TB available with the two 1TBs and the 100GB minus overhead.

Just out of curiosity the other day, I went to use the Drobo calculator. I wanted to simulate a drive outage. The closest to my 100GB I could find on the app is an 80GB (close enough), so I simulated two 1TBs and one 80GB, for a total of 1003.8GB of usable data. I removed the 80GB, and as I expected, ended up with 930ish GB of usable space. But what shocked me is I reset it (two 1TBs, 1 80GB), and then simulated a failure of one of the TBs, and I end up with 72.8GB of usable space. However, if I simulate having only the two 1TBs, and I simulate the failure of one, I end up with 464GB of usable space.

So my question is, am I really just hurting myself by having the smaller drive in there? Should I just take it out and go with the two 1TBs for now? I know I should get more big drives in there but that will come eventually. But for now, should I just ditch the small one and use the two TBs? What if I keep all three – what happens if I have, say, 200GB worth of data, and I lose one of the TBs? If my “usable” space goes below the data I have on there now, what happens??

Thanks in advance! Sorry for making a short story long…

The contrast between 1TB and 100GB drive capacity is too high.

When I first got my drobo I did some experiments with 750GB, 320GB and 2x80GB drives.

The point was to fail drives so that usable space is LESS than actual data on drobo.

The results was exactly as I expected - I did not loose data, but drobo said that it can’t protect my data against any more drive failures.

So my advice is that if contrast between HDD capacity is so high, then don’t bother with those small drives …

Makes sense. Thanks, Bytec!

Exactly. You’ll also use less power and generate less heat.

Stick the 100GB drive in a mobile enclosure or give it to a friend. :slight_smile:

To bring closure to the thread (at least for me :wink: ), just thought I’d let you guys know what I ended up doing. I ordered another 1TB drive (hey, it’s cheap enough, and I’m paranoid enough to worry that there’s that minuscule chance that the two TBs in there now would fail simultaneously, since they are the same brand/type/size/purchase date). I popped out the 100GB, and Drobo Dashboard told me it detected a drive removal, and the lights never flickered. I expected to get flashing lights to indicate it was re-indexing, but I guess the data on there is still small enough to where it did it pretty fast. I let it sit for a while just to make sure. Then I popped in the new 1TB. Again, Dashboard told me I put in a new drive, but the lights never flickered. It’s now humming along happily with the extra TB drive. I <3 my Drobo!