Striping data to new larger drive

Apologies for the noob question but if I am at max capacity in my drobo and I swap in a new larger drive, will it include the existing data onto this new drive and leave the remainder as part of my overall storage capacity. I have a mixture of 2TB and 6TB drives and I want to incorporate a new single 8TB drive.


hi martin,
while there might be some other limitations in terms of drives and max sizes (such as not using drives which incorporate SMR features), the overall management of data as i understand it is as follows:

if drives are in a drobo, and data is stored on the drobo, then the data is spread over all disks automatically by the drobo (including data protection features for 1 drive, in SDR Single Drive Redundancy mode, or 2 drives in Dual DDR mode)

assuming SDR, then drobo will essentially use up the (total raw) capacity of your Largest drive for Redundancy.
(in your current case, then 6TB of raw capacity would be used up, though this would actually be spread out throughout the drives)

so assuming that you were to swap out a suitable 8TB compatible with your setup, then 8TB’s worth of capacity would end up being used up/reserved for protection.

if you have a moment to post back when you can, with your drive slot details if you wish, along with whether you have SDR or DDR currently enabled, we can try to flesh this out a bit more for you using your actual capacities.
such as:

Slot 1 = xTB drive (western digital WD xyz)
Slot 2 = xTB drive (etc)
etc or something similar :slight_smile:

Thank you, Paul.

DDR and SDR are not enabled. Slot 1-4 are occupied with 6TB drives and slots 5-8 have 2TB drives in them. They are all enterprise Western digital drives. My intent was to swap out the 2TB in slot 5 and replace it with an 8TB Enterprise WD drive.

thanks martin,
it sounds like your setup of the following would work out to be this: (in TB)

6+6+6+6+2+2+2+2 = 32tb raw capacity
-6 = 26tb available for use
26*0.9 filesystem overhead (approx) = about 23.4TB available for use

if you have that amount of abotu 23tb usable, then it looks like you are on the minimum protection level which is SDR (as all drobos will have at least that level of protection if DDR is not enabled)

one thing that i am not sure about though, is whether you would be able to upgrade (currently) to a larger drive yet, because as far as i know, your model of drobo has a “Maximum System Capacity: 32TB”

it may be worth waiting for another user to help confirm if this is addressed in another firmware or if the 32TB is the Raw amount which you have currently, or if it is for the usable, and whether DDR could be enabled to utilise any excess above 32TB, though to be honest if you already are in support it is probably best to raise a ticket with the team before trying any update, just to play safe… (and if you have a solid production system at the moment, it may even be worth raising a pay-per-view ticket for a relatively lower cost if out of support, for peace of mind)

Thank you, Paul. I just added an 8TB drive to my drobo and I’ve gotten the following two messages on the drobo dashboard.

1st message: Data protection is in progress. You may continue accessing your data, but please do not remove any hard drives with blinking yellow/green lights.

2nd message: Red Alert. Drobo detected a hard drive failure. Replace the hard drive indicated by the blinking red light.

My method of removing and adding the drive was hot swap. Have I done something wrong?

hi martin,
in this case hot-swapping is the usual process for upgrading a drive, though can you help clarify which of the drives is actually showing as blinking/flashing red light?

it might be for another older/smaller drive (which maybe could not deal with extra usage stress from the recent rebuild, but was if for the latest 8tb drive you added?)

(by the way, was that 8tb prechecked/scanned in any way before being put in the drobo?)