Getting email that Drobo is critically full but only 2/3 full and no red lights

Dear Twin Tiger,

Thanks. I have backed up my Drobo to a Time Machine ext HD and installed Drobo Dashboard 3.6.1 and it is working. Below and in 3 more emails to follow are the screen shots of the dashboard. (My email with 4 screenshots was rejected.) Please let me know whether something is needed and whether I can upgrade of OS 12.3.1 on the Mac.

Thanks so much,

PS Where are you? I see a big time difference for us.

Hi Sally,

Great to see those images. I note that your firmware is up to date. :slight_smile:
Your Drobo looks healthy - with one minor issue I have noted but need some further info from you.
Can you post one additional screenshot - on the Capacity tab, there is a ‘Usage’ view - can you post that to double check the assignment of the available volume?

Then under the Status tab, there is the system information drop down menu where you can select each of the HDD in turn to analyse them. Whilst all are currently ‘green’, at the Health line, are any of them marked also as ‘healed’?

Back to your initial concern as well, regarding the emails - how often are you receiving them from Drobo?

Lastly, I’m not in North America, but even then I only check this site once a day and not at a fixed time when I do - sorry for any delays in response.

No they all say “good”.

I received those emails a bunch of times from 4/18/22 through 4/20/22 (there were 4 on the 20th that didn’t fit into the screen shot):

I wasn’t concerned about any delay but had a sense you were elsewhere because of the times on your emails.


Thanks for the extra snapshot of the Usage. Your setup appears completely normal. Was the last notice 20Apr? None recently? Now that you have the latest Dashboard installed perhaps monitor it for a week or so and report back if you get a notice again?

For housekeeping you can also run Disk Utility from the Mac on your Drobo drive to check its file structure as well. I do this approximately every quarter for my Drobo 5D.

It is also worth pointing out that a result of your mix of HDDs in your array, you have 931GB provisioned for expansion - this means that you cannot use that space (yet) as it cannot be replicated (just the way Drobo works). If you were to replace a single 2TB HDD with a 4TB HDD (CMR not SMR) you would revert that protected space to available space and use all your HDD’s more efficiently.

To see this in action virtually go to the Drobo Capacity Calculator, select your 5C and drag the HDD symbols into the Drobo to match your existing HDD array, then drag a 4TB HDD over any 2TB in your array to see the impact and improvement in available capacity.

Dear Twin Tiger,

I am running First Aid on the Drobo in Disk Utility now. It’s fine.

I did the capacity calculator but it doesn’t mean much to me…
–With the 4 TB in place it says “0” reserved for expansion…?
–I don’t do dual disc redundancy, do I? I already have redundancy, right?

I did buy the 4 TB HDD.
–Is it ok to remove a disc with a green light since there aren’t any yellow or red lights?
–I can’t tell which of the 2 TB discs might be older or slower from the info I see. Does it matter?

Thanks for continuing to help me with this.

Good news on the First Aid result. No need to do this regularly - 3 or 4 times a year should be fine.

So you are correct. From your existing array there is space that cannot be used as it is reserved for expansion. If you slot in a new 4TB drive then you can recover that space (and get a bit more). The objective is to have “0” for expansion.

You don’t have dual redundancy set on the Drobo under your current arrangement - as long as you have an external backup of your Drobo and it is kept up to date, you automatically have ‘dual redundancy’ of your data. Enabling dual redundancy on the Drobo is (IMO) not necessary as the single point of failure is always the Drobo itself, meaning that if your Drobo fails you lose everything. Your current set up allows you to have a single HDD fail, and not lose your data - a normal RAID setup (same as mine). If your Drobo fails, you also now have your external backup to recover data. So I would recommend that you keep your external backup up to date (each week or month to suit you) and back it up if you create/add some really important data (eg photos of a wedding or graduation).

I need you to be really careful on your new 4TB HDD - was it CMR or SMR? Drobos don’t like SMR HDDs and they can risk you data. Can you be really specific about what you purchased? Sent an image back here if you are in doubt.

Assuming you have updated you external backup, and the replacement HDD is a CMR you can indeed pull out any 2TB drive (it doesn’t matter which) and slot in the new 4TB drive. Do this towards the end of your day, as it will take some time for it to repopulate and redistribute the data across all the drives, and it is best if you are not accessing the Drobo whilst it ‘does its thing’ as it just slows down the process. When you extract the 2TB drive all the lights will blink yellow and green - inset the new 4TB drive as soon as you can but in a measured way and ensure it ‘clicks’ completely into place (two thumbs pressure). You will also get a series of warning emails - normal, as well as one that recognises the new drive has been inserted. As long as the Drobo is blinking yellow and green then it is fine to leave as is - you can track this all happening on the Drobo Dashboard as well.

Generally it will take 1TB of data = 1hour (+/-) so with your current 5TB of data + 3TB of protected data it should be 8 - 10 hours. When finished, all lights should be green and you will get an email to confirm completion.

I’d consider budgeting to get the capacity for Dual Redundancy before you hit 4TB drives in all slots though, or at least having a full backup, or knowing you can re-create the enire content of your Drobo (assuming it’s say only a target for backups that can be re-created)… have a look at RAID 5 and Uncorrectable Read Errors (
To be fair with a Drobo it’s not quite that bad, (You only have to concern yourself with used capacity rather than TOTAL capacity, compared to plain RAID5… but even so, it 's a consideration…

Thanks! I’ve never switched out a drive that didn’t have a red light warning on it and feel better knowing what to expect. I didn’t know about CMR vs SMR before so I can’t be sure about the discs in the Drobo but this one is CMR(see below). Is there a way to check the discs in the Drobo?

I do wonder about the rpms because I got this one @ 7200 and I wonder whether the entire Drobo is limited to the speed of the slowest disc. I probably tried to get faster ones but who knows what I got before?

Thanks again for clarifying so much for me. Drobos are not the sort of thing one can ask just anyone about.

Dashboard > Status
Click on each drive bay, google the information.

Hi Sally,
As @cyber_beardy suggested, you can check your existing drives via the Dashboard. If you find any SMR drives, they should be replaced.

Ideally any Drobo also works more efficiently with the identical spinning HDDs, but they will work happily with a mix as long as you are not doing extended and intensive read/writes. Their claim to fame is the ability to mix and match HDDs so don’t be too worried if you have a few 5400rpm drives.

Perhaps this whole episode will allow you to prioritise your next upgrades to your 5C, in addition to your OS upgrade ahead?

Anyway it looks like you have a new 4TB to install and I look forward to reading about your success.


I did google the drives as Cyber_beardy suggested; the 2 TB and 4 TB HDDs are good(7200 rpm and CMR) but I don’t see CMR or SMR on the 3 TB Hitachi drive:

I have about 7 hours left then I’ll upgrade my OS. Do you mean buy another Drobo when you say upgrade my 5C?
I’m happy to have gotten this far!

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I did google the drives as Cyber_beardy suggested; the 2 TB and 4 TB HDDs are good(7200 rpm and CMR) but I don’t see CMR or SMR on the 3 TB Hitachi drive:

I have about 7 hours left then I’ll upgrade my OS. Do you mean buy another Drobo when you say upgrade my 5C?
I’m happy to have gotten this far!

Hi, Twin Tiger,

Please don’t worry that you will never stop hearing from me—I am traveling soon and am just trying to tie things up before I leave so there is an end date to my questions!
I LOVE having an opportunity to ask questions.

Here’s one which I could “google” but would like the official recommendation: how to clean the very dusty Drobo with the discs in it? I could vaccuum or blow air at it (which doesn’t sound safe). It’s filthy. When I leave for a couple of months I’ll dismount it and loosen the discs, but want to clean it properly. I looked on the Drobo site and didn’t see anything.


Hi Sally,
Your HGST Hitachi is CMR, so no problem there,

For upgrading, I was referring to larger HDDs in the future as your data increases over time. Hopefully there are a few more years for your 5C ahead!

To clean your Drobo, fully shut down and disconnect the power then mark your HDDs in order before you extract them. A small domestic vacuum cleaner and soft moist cloth wipe down should be sufficient to clean the unit. Pay attention to the front cover - this you can clean more regularly as it is the inlet for air drawn into the Drobo carcass by the fan, When clean, reinsert your HDDs in the same order, reconnect and restart.

If this helps, here is a link to the post when I upgraded to Monterey. Note the 2 overrides to System Preferences to allow the Drobo Dashboard to operate fully.

Dear Twin Tiger,

OK!! I’m all set. The new HDD is in, the OS is 12.3.1, and the external drive has the Drobo backed up. I didn’t have a problem with the system preferences, although I didn’t see 2 files specific to the Drobo Dashboard in Full Disk Access (just one, I think, which was already checked).

Thanks so, so much for all your help!!

Now I can print some pictures before I put the thing away while we are gone.

Sally - Good to hear.
Enjoy your break.