An extra (unwanted) Volume

Drobo 5D (with 5 HDD) connected by USB to Windows 8.1 PC as Volume G:

I just upsized one of my drives and the (latest) Drobo Dashboard reported that it was recovering, and it now has and is reported as healthy. However the new HDD has been added as Volume H:. The overall capacity seems to have increased which is good, but I want a single combined volume.

What do I need to do to combine the volumes into one without any data loss?


It is NOT the “new HDD” that has been added as a new volume. There is no way to address individual disks.

The disks together make a “pack”.

What has happened is that the available storage capacity of your disk pack has exceeded the volume size that you chose when you first formatted your Volume G. Therefore Drobo has created a second volume for you to be able to access that additional capacity.

lets say that you chose 4Tb when you first created your volume G.

if Drobo only had 3Tb of capacity that was not a problem.

if you added / upgraded disks so that Drobo now has 5Tb of usable capacity, then you cannot address that extra 1tb of space using your existing 4Tb volume.

So drobo will create a second 4Tb volume for you.

if you upgraded enough so that you had 9Tb of space, then drobo would create a third 4tb volume, as two 4tb volumes wouldn’t let you use all of your new 9tb of space.

This is why many people choose 16Tb as the initial volume size - as it will allow them to keep adding more disks/capacity without having to have multiple volumes to address it.

You are now stuck with whatever volume size you initially chose, and Drobo will continue to create additional volumes in multiple of that size as you add more space. You cannot change this without resetting the Drobo and wiping it.

(DroboPro and Drobo Elite allow you to manually create volumes and chose the size as you wish - if you had one of those you could create a new 16tb volume on your pack, copy everything from the smaller volume to the larger one, and then delete the smaller one. but i do not think that the lesser Drobos allow you to do this.)

What DocChris said is correct. This is how Drobo works… due to Thin Provision Volume(s) and also the initial size of the Volume you choose when you first setup the Drobo.

Read my posting in this thread for more details…

there are also pros and cons to having multiple smaller volumes,
(some media players can only read the content of the 1st volume of a device, such as on a networked model)

if having a 2nd volume is not really that much of a problem (which it probably isnt) - then you might as well leave it as it is. (just try to remember to look at the drobo leds and dashboard to keep a more accurate track of the space you are using, because the 2nd volume will look like it has more TB free space than your drobo actually has.