I’m running low on space in my 5d (I think I purchased some time in 2014). I currently have 3 x 6TB and 2 X 4TB.
I was looking in to getting 2 more 6TB drives since that is all I thought it could handle. I was pleasantly surprised to see it now accepts 8TB drives!
I read somewhere though that I can’t just swap out what I have for 8 TB, right? I have to copy the data somewhere and reset the drobo after installing the new 8TB drives? Even if it’s just one or two drives? (Say I replace the two 4 TB with two 8TB).
If this is the case I’m wondering where people put 18TB of data real quick during this process 
I’m hoping I have it wrong and I can just switch them out like I have with the others along the way.
Thanks for any help you can give!
hi kate,
for the 8TB drives, there are some incompatible ones (also listed on that page) and problems with the way SMR (shingled) drives work.
this page (and a link off it too) should have lots of info for you about the larger support for volume sizes.
https://myproducts.drobo.com/article/AA-01766
and i guess the quickest way to backup 18TB (if you do not already have another das ready to use) would probably be through the use of a stand-alone caddy (such as an icy dock usb) and some blank bare sata drives that you could hook up to it 1 by 1, and copy / paste / verify your data on. (you might need to check on amazon to see what drives people usually get with which caddy because some caddies can only handle drives up to a certain size)
but… can i check if you specifically need to have only 1 single huge volume, or could you still make do with an additional volume (or drive letter / icon) on your computer? (and do you know which method of redundancy you are using at the moment, such as single SDR or dual DDR?)
for example, if you were to end up replacing the 2x 4TB drives, (one at a time though like youve probably done before) into 6TBs, you would end up with this:
6+6+6 +6+6 = 30TB raw
30TB (-6TB for sdr) = 24TB
24TB (*0.9) for usual filesystem overheads) = about 21.6TB
as far as i know, this should be ok in terms of the unit handing the raw capacity, and it should not need any reset etc, though you might then be around the 85% used space mark, and get a yellow drive light.
(btw what is your current dashboard showing you in terms of used and free space?
Thank you so much for taking the time on this Paul!
I had never heard of the icy dock usb’s, thank you for pointing me in that direction, very cool.
Current situation:
I have single redundancy set up currently (bad idea?)
All of the drives I have are WD Black
Top 2 slots are 6TB and are green
Next slot is 4TB and it’s at a yellow warning
Next slot is 4TB green
Last slot is 6TB green
It never even occurred to me that the order of the drives might make a difference, does it?
For capacity it says I have 18.08 TB total: 15.42 TB used and 2.66TB free space
When I replaced a drive last time (swapped out 4TB for 6TB) it did create another drive icon. I panicked at first but after some googling it seemed to be fine and that the Drobo was handling it all as one drive, even though there were two on my desktop (please let me know if that does not make sense!). I would be able to use the drives separately and wouldn’t mind that, if that’s what it took.
After reading your calculations about buying 2 more 6TB drives and only getting ~3TB of space doesn’t seem great. In an ideal world, I’d love to replace them with 8TB drives but am worried I’d need to move the data and reformat (this is where the icy dock comes in right?).
Is this correct in terms of calculations if I upgraded two of the drives to 8TB?
8+8+6+6+6 = 34 raw
30TB (-8TB for sdr) = 26 TB
26TB(*0.9) = ~23.66 TB
I noticed it says the 5D has a max volume of 64 TB. But if I have 5 drives of 8TB, isn’t that only 40TB? My mind might be spinning 
Thank you
Kate
thanks for the info kate,
ah if it shows you 64TB max volumes then you might already actually have the newer firmware… for example as shown here: http://files.drobo.com.s3-us-west-2.amazonaws.com/webrelease/5D-Mini/Release-Notes-firmware-5D-Mini-3.5.0.pdf
(if you check some of the tabs in dashboard it should show you the version of the firmware - only have a look though)
in terms of the drive ordering, (for your context) i dont think it makes any difference for you, and the current lighting of the drive bay lights is just taking into consideration of what you have at the moment:
for example when you mentioned this:
Top 2 slots are 6TB and are green
Next slot is 4TB and it’s at a yellow warning (this is usually just because 4TB is the smallest drive you have)
Next slot is 4TB green (this is not yellow, because the drobo usually flags the 1st smallest drive, which is the one above it, & if that one was upgraded then this one might then now be the smallest of the drives and go yellow)
Last slot is 6TB green
(the fact that they are a solid green, plus a solid yellow, is usually a good sign that the drive is currently ok, rather than a failed light which would be flashing red)
with your current drives, it looks like you are using little more than 85% of your space, (which is what usually shows the first solid yellow light). When you mention you are using SDR, that is ok, and matches up with your total and used and free space values. Ideally DDR is always going to be safer than sdr, and can help you protect against 2 drives going wrong, though i dont think you will be able to select DDR mode (if you are low on space) and it could be greyed out until you upgrade some drives.
having said that, since you are only on SDR at the moment, it is always a good idea to backup your data first, (if you can) or at least the most important stuff because just in case a drive you already have is getting on a bit, it might not cope as well with the rebuild process of upgrading… and as each drive upgrades, they all will go through this process and with sdr you would not want more than 1 to have any problems during rebuilds etc.
having said that, all of the drive upgrades i have carried out, have been ok but its always goot to play safe if you can especially if its important.
(and dont worry if you head is spinning, am sure its not at much as the drives are) 