Nonstop disk activity

My Drobo 5D3 has been making drive noises, pretty much non stop for weeks. I have tried turning off every service and application I think of, but nothing makes it stop. It even keeps making drive activity noises when the host Mac is being rebooted! Also, IO performance is pathetic, see attached image.

I recently had to replace 2 x 4 TB drives, 1 at a time, over a couple of weeks, with 2 x 6 TB drives, as the capacity was getting low. The Drobo mis-identifies the 2 6 TB drives as ‘SSD’ drives.

There is an mSATA card in it, and the health is reported as ‘Good Life (47%)’

Any ideas? I am ready to chuck this thing

I just unmounted both volumes of the Drobo and the drives are still doing stuff non-stop. I just rebooted into safe mode (with no access to the Drobo as there are no kernel extensions loaded) and there is nonstop drive activity. I am just about ready to chuck it.

Perhaps it’s busy doing background tasks like data layout, etc. All this happens independent of computer connections.

Sure, but does that take literally weeks of time, 24/7?

Maybe the Directory is compromised? If the Drobo is formatted in HFS+, have you run the Mac Disk Utility on it?
I also run a 3rd party disk utility on my 5D each month which picks up issues Mac Utility does not.

That’s a good suggestion. I already ran disk utility on both the main partition and the time machine partition, and neither had errors.

OK - Can you advise your capacity and % full for each partition on your Drobo?


The Drobo’s capacity is 16.17 TB, with 4.65 TB free (29%).
The Backup partition is 2 TB in size and has 1.19 TB in use.
The other partition has 10 TB in use.

After powering the Drobo down the other day (the noise is annoying) and starting it up again, I received a notification that “This device needs to be rebooted to complete some optimizations. Please unplug the Thunderbolt cable and Drobo will reboot automatically.”

I did this, and it hasn’t helped. It did the same thing yesterday when I needed a break from the noise, and I got the same notification again.

OK - a bit more info please:
Can I assume that the noise is just being generated by the HDDs?
Confirm set up is RAID 0, and not Dual Disk Redundancy?
Please identify If your partitions are confined to specific HDDs, or across the entire Raid
Can you list your HDDs from top to bottom with their make and size?

Yes, the noise is definitely drive activity noise.

Yes, single disk redundancy.

Not sure how to confine a partition to a specific HD (or the such a thing was even possible), so I’ll say they are across the entire raid.

I had 5 x 4TD WD Red (WD40EFRX-68N) drives installed, ran low on space (2 TB left) and added, as directed by the Drobo, a larger drive. I added a 6 TB WD Red (WD60EFAX-68S). The Drobo thinks it is an SSD.

All the drives are 5400 RPM.

After 30 hours of recovery and a week of non-stop drive activity it settled down.

It ‘ran low on space’ again, and I added another 6 TD WD Red, which it also thinks is an SSD.

There is a 240 GB mSATA drive, that the Drobo reports as being “Good Life (47%)”.


I also booted into safe mode, and the Drobo drives were still chattering away.

Hey, thanks for the clear status. It’s got me stumped!

If you have access to other external HDDs you could try a full reset of the Drobo configuration and reformat all 5 HDDs, but you would need to offload/copy your data to your other external HDDs first, and then reinstall it all afterwards. Otherwise I’m a little lost for other options.

EDIT: Just an aside, the Time Machine partition is a complex series of compressed and cross linked files. My experience is that copying it from one HDD to another is a LONG process. Whilst that could explain your length of time for chatter, it does not explain the noise, if truly excessive.

Thanks for trying. It’s more than Drobo is doing.

I’d rather not have to shuffle around 10 TB of data, but I don’t really see an alternative at this point.

Just to clarify, the noise that is being made is just the regular fan noise plus the regular noise that 5 drives make when they are busy reading and writing data, and is to be expected when I’m doing something. Part of the annoyance I have is with the constant sounds, as well as the wear and tear on the drives being under constant load, for no apparent reason.

I probably wouldn’t bother with trying to migrate the time machine backups, as yes, they are quite unwieldy beasts.

Thanks again for your efforts.

I was thinking about your situation today, and I wonder if your Time Machine/Backup partition is causing a blockage in overall duplication across the Drobo despite it being happily in use previously. If you are willing to try, could you offload a minimum of 2-3TB of data that is NOT associated with the Time Machine, and see if it settles down?

My rationale (non-tech here but …) is that the duplication on the Drobo means your Time Machine might be clogging the overall efficiency of the RAID due to its size and complexity whilst dealing with the amount of other data currently in the Drobo despite it showing 29% free, so by clearing out some space, it “could” become stable. If that works …(!), then you may need to purchase some additional larger HDDs and have them replace some of your 4TBs before reinstalling the removed data.

I have nothing but a hunch to go on, but thought I would share it.

EDIT: can you confirm your Drobo has the current firmware updated and the Drobo desktop app is updated as well?

Firmware 4.1.3 [14.46.108761], Dashboard 3.5.0.

I’ll see if I can free up some space and see if that make any difference.


The Finder is reporting that it will take about 4 days to copy 500 GB of data off the Drobo.

If I buy a year of DroboCare, any idea if there’s a guarantee of this being able to be resolved?

Good luck with the data dump. Based on your earlier posts, it makes sense that the offload will take time, so it’s smart to do it in small chunks. Make sure you corroborate the offloaded data before you delete it from the Drobo (sorry, just stating the obvious). Keep us updated on the status when it makes sense.

Just another afterthought on your system.
Can you confirm that your Time Machine has unchecked the ‘Back-up Automatically’? This will prevent continual snapshots, hourly, daily and weekly backups in the background.

Here’s an update: I have copied everything off this Drobo 5D3 and factory reset it.

Upon reset and rebooting, there is still non-stop disk activity, even before a volume has been formatted on it.

I tried migrating these 5 disks to another 5D3 (before resetting) and there was also non-stop disk activity.

This seems, to me at least, to be related to the fact that the Drobo insists that the 2 6TB WD Red drives are SSDs.

What a frustrating and waste-of-time experience this has been, and I’ve still yet to receive a response from Drobo.