So recently purchased a drobo 5N and so far really happy and easy the installation, tonight will be the first backup (around 800gigs), my question on the storage i see that it saves on reserve 1.99tb which i thought it was odd any idea? see picture
hi i think this is just the way that the 5n in single drive redundancy, essentially reserves about the same size as your largest drive (overall) for protection. the idea behind SDR is so that if any 1 drive fails, it can still protect your other drives and data.
there is also a dual (DDR) mode that can be enabled if there is enough space, which can help protect against any 2 drives failing. that will take up about the same size as 2 of your largest drives, though is worth it where possible. (you can technically also switch back down to sdr if you need more space again, but may not be able to switch back to ddr if there is not enough space)
i know the feeling (i used to try utilising free space all over the place on computer)
but in this case im not aware of any way to disable the default sdr protection.
one thing to bear in mind for the future though, is that a good way (with sdr) to gain more efficiency, is to actually use at least 2 compatible drives (of the same largest size)
and for DDR mode, to actually have the 3 largest drives the same size.
(these above steps will allow the drobo to only reserve the necessary space overall, for the sdr or ddr modes, because if you only have say 1 huge drive, and lots of smaller drives, the huge drives equivalent amount of space will be reserved, even though all the smaller ones wont necessarily add up to the same amount, so if you stick with at least 2 the same size where possible, then you can usually gain usable space when another one is added in)