Drobo FS migration to Drobo 5N


I recently got myself the Drobo 5N to upgrade from a Drobo FS. Since I wanted to use the new storage format, I purchased 2 8TB HDDs for the 5N and started to move files over from the old FS.

The FS had 2x 6TB and 3x 4TB HDDs which I partly wanted to move over to the new 5N. After starting to move many files and the 5N filling up I removed one of the 6TB HDDs from the FS and moved it to the 5N.

But now the FS is not rebuilding the system but stuck in “add a drive” and red error mode for the first drive I moved. It has 3 TB free space.

What can I do to force it to restart rebuilding so I can later move a second drive out of the old box?


hi ccmatrix-1, are these the same drobos from your other post last year here?

it may be due to the drobo still reclaiming free blocks (which dashboard should show by regularly updating the free and used space values), but also as the largest drive in the FS currently sounds like it is a 6TB, it might be trying to reserve that much space over the other drives for data protection, and you might need to wait a bit more, or to try copying some more files over to the 5n (especially if now has a lot of extra usable space), and then once happy with the file copies, you could try deleting the copied files from the FS, and it should then be able to trigger the rebuild for you.

can i check how much used and free space is showing on the FS currently, in percentages and values?


Hi Paul,

First of all thanks for your respone :slight_smile:

Yes those are the exact same drobos from that post. I finally took the step of moving to a new 5N to “beat” the 16TB limit.
I am moving the files over using my Windows 10 PC and TeraCopy Utility.

At the moment the Drobo FS has a Capacity of 10.90 TB, 6.71 TB Used and 4.19 TB Free while the Drobo 5N has 12.61 TB Capcaity, 8.75 TB Used and 3.86 TB Free.

Curently the Drobo FS is loaded with 1x 6TB and 2x 4TB while the Drobo 5N has 2x 8TB and 1x 6TB. The final setup would be 2x 8TB, 2x 6TB 1x 4TB for the Drobo 5N.

Is it possible that the Drobo FS does not enter rebuild because I am still moving many files out of the system? I read somewhere that the rebuild and cleanup phases of the Drobo might take a while to initialize. I just hope there is a better way to make it start rebuilding than to stop moving files and waiting for days.


ah thanks for that and for more info,

i dont think it should take that much time, though if there is a protection feature, and if the fs also carries out monthly data scrubbing (verification) of data, there is a possibility that it could be wanting to finish the verification first, before carrying out a rebuild… if this is the case though, i would imagine it to take only (if we can call it that) about 1 day per 1TB of data that you have, and then the same amount of time to do the actual rebuild.

if this theory holds true, then depending on how much you were using the drobo with accessing or modifying etc, hopefully in the next couple of days if would be ready, but if you can please let us know how things go we can see how the theory goes :slight_smile:


I let it sit for 2 days but no change.

Then I realized that I had enough free space for dual disk redundancy. So i switched that on and now it is rebuilding for dual disk redundancy. Interesting enough it shows green/yellow flashing in the “All Drobos” dashboard view but in the detail view it is still first drive red, others green. The physical drobo also shows first drive red and others green. So I am curious on what happens now. It has about 5 TB of data so it should be done in a day or so.

Will let you know when that is done.


oh ok, that is interesting about the visual representation of all drobos and dashboard details.
i would have expected the physical drobo to always show the very latest/most current status in terms of flashing lights or colours… (an exit and relaunch of dashboard may unlock a possibly locked dashboard state, but probably best not to touch it or change anything until it completes) and i keep my fingers crossed for you in the meantime


It blinked and blinked and blinked but I couldn’t see any progress. Also the Drobo FS got very slow for any read operation so working with the files on it was starting to be painful so I basically gave up.

I switched back the FS to single disk redundancy which made it more responsive while returning the the red indicator. I bought another 8 TB drive for the new Drobo 5N so it had enough space to store the remaining data from the Drobo FS. I am now moving all remaining data from the FS over at ok speeds and can then reset the old FS when it is empty.

Thanks a lot for your help.

Something I learned along the way: I used mailgun as a mail service in their free version to let the Drobos send me status mails without having to add my personal mail credentials into the Drobo. Works very nicely so far :slight_smile:


Maybe my Drobo FS doesn’t want to be replaced :smiley: Now that it lost the battle it actually started to do the rebuilding. It tells me approximately 266 hours remaining with 3,8 TB used. Meanwhile the moving off of the data is progressing and speed is varying between 3 MB/s and 6 MB/s. So it will still take a few days to complete but the end is in sight.


ah ok please us know how things turn out
(yes, using the drobo at the same time will slow both operations down, but once you stop copying a batch, i think the estimate should be able to recalculate to give a better estimate… though most probably it will work out at about 1 day per 1TB of data that you have on it, though extra for any data that was being copied at the same time)

i’ll add mailgun to the research list :slight_smile:


So the rebuild went through and all my data has been moved to the new Drobo 5N. I am now in the progress of upgrading the other FS to the maximum with the 4TB hard drives that got available from the retiring FS. So far that works well, it triggers a rebuild after I replace a 3TB with a 4TB drive and then takes about 30 hours to complete.

Thanks again for the help.

As soon as all the 4TBs are in the other FS, I want to basically reset the old FS with 3x 3TB and gift it to my parents as a storage for family pictures etc. What is the best way to do a clean reset?


ah thanks for the update ccmatrix-1 am glad the process is working out :slight_smile:

if i understood correctly, once your have finished, you would have 3 x 3TB drives (that used to be part of a diskpack) that you dont need anything else on those drives?
if so, you could perform a full reset via dashboard.

(this should be ok enough if you give your drives to your trustworthy parents, and that way the diskpack and volume(s) will be set up and ready or easier for them to use.)

if you wanted to add in an extra layer of security, you could do the following:

  • to shutdown the drobo, and to remove the no-longer-necessary-diskpack-drives
  • to connect 1 diskpack drive, either up to the computer, or to a different, basic usb standalone caddy
  • to format it on windows (for example) as a basic nfts drive
  • to use a free program similar to your name :slight_smile: called ccleaner.
  • and to run a basic drive wiper routine. (such as free space only and unless you had super secret financial info etc then it should be fine)
  • then to do the same for the other diskpack drives 1 by 1
  • and then you can set up the drobo fresh with the drives, and prepare it for your parents.