Unallocated space?

Hi everyone,

I was running out of space on a 2nd gen, 4-bay Drobo, so I just swapped out a 2 TB drive for a 4 TB drive. (Currently 3 x 4 TB, 1 x 2 TB.) While the Drobo is rebuilding the array, Drobo Dashboard reports that there is 1.06 TB of “unallocated space”.

Is that normal? Why wouldn’t DD show that as “free space” instead – or will it show that after the Data Protection stage completes?


It looks as though you’ve grown your existing volume as far as the maximum size you initially allocated to it and the remainder is available as unallocated space. You can allocate it to a new volume. When you’ve done that it will appear as free space.

Oh. I must have done that a few years ago. Can I merge this new space with the existing volume? I don’t want a new volume.

I suspect at the very first initial setup… you didn’t create and format the Drobo Volume as the MAX 16TB supported by Drobo. You may have previously created a 8TB volume instead.

Over the course of adding more higher capacity drive such as 4TB drive(s), at one stage … you should have encountered Dashboard prompted you to create another new volume but you may have cancel it.

This is why now you have your original Drobo Volume, and with extra unallocated space.

  • These unallocated space can be used to created another (2nd) Volume*

*Note: You cannot merge unallocated space or the new created 2nd volume into the original Drobo Volume.

The only way to obtain a SINGLE large Drobo Volume… will be manually copy out all existing data from the main Drobo Volume into another temp storage. Then reset the entire Drobo then re-setup anew, this time choose the Max 16TB volume.After that copy back all the data from the temp storage back into the Drobo.

**You can create 16TB Volume in Dorbo using the Drobo Dashboard, even though physically you might not have 16TB real disk space. This is called Thin Provision volume.

Ah, okay. That’s what I’m doing now. I’ll synchronize everything from my Drobo 2 to my Drobo S, reformat the Drobo 2 to max size, and sync everything make.

Thanks for clarifying that.