5N requests more space

Dear community,
some weeks ago, my drobo 5N marked one drive with red light and reports about not enough storage. I replaced the 1TB hard drive by a 4TB one. After that, the next drive turned red and wanted to be replaced. So I did. And again… next drive turned red. Meanwhile I replaced ALL drives by bigger ones (which cost me some money), but Drobo is repeating this loop by turning drive 0 red again :frowning:
Meanwhile, there is definately plenty of free storage available. Turning the device off and on does not help.
Would be great if anyone can help me solving this annoying issue. The drobo is the only backup for most of my files.

Many thanks.

Well if all the original drives were the same size, asking for 2 to see any increase in available storage is expected, with dual redundancy you need to replace 3, as playing with the capacity calculator will demonstrate.

At present buying drives for Drobos can be a minefield, with many manufacturers introducing SMR drives for certain product lines without mentioning the fact. As noted in this KB article


  1. SMR drives including (but not limited to) Seagate Archive and Hitachi Ultrastar drives are not supported for use in any Drobo.

Something that ought to be prominent on the Drive Selector page & isn’t, such drives misbehave in various ways.

So one of the questions becomes, what drives did you buy?

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Yes, meanwhile the Drobo 5N is running with 5 HDDs, 4TB each. Dual redundancy is deactivated (and cannot be activated due to the red alert).
Here are my drives:
Bay-0: Western Digital WD40EZRX
Bay-1: Seagate ST4000DM000
Bay-2: Western Digital WD4000FYYZ
Bay-3: Western Digital WD4000FYYZ
Bay-4: Hitachi Deskstar HDS72404

Red alert is currently at bay-0.
Would you say one of the installed drives is causing the problem? If so, is there a way to remove/replace it without loosing my data?

Well the WD drives don’t appear on the SMR sh*t list The others my google-fu seems to have deserted me for.

What’s dashboard showing for capacity?

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there are 14.35 TB available for data.
0 for extension.
3.81 TB for protection.
25.47 TB rest capacity.
Used space is at 100% (=14.35TB)
I know that the files I own cannot need more than about 4TB. These number simply don’t make sense to me
BTW, the Seagate can be found here

and the Hitachi should be this one

Any idea?

Turning up those drives to buy wasn’t the issue, turning up properly detailed technical specifications was, the full drive manual, the info needed tends not to be on the basic data sheet.

With only about 4 GB of data I’d personally back that up & do a full reset on the drobo to reformat it, then restore, if it was one of the direct attached units like a 5C I’d suggest running chkdsk or the mac disk checker, but they don’t work for network drives, The built in tool is apparently slow & potentially destructive of data on the NAS products & backing them up before running it is recommended anyway, though it’s your data and your risk if you want to try that without copying the data off. But misreporting the amount of data there is likely to be a filesystem issue.

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4TB, not 4GB.
Anyway, I backed everything up and did a total reset of the Drobo. During feeding with some HDD, I realized it is the SEAGATE HDD, creating massive problems. Drobo was unable to fully boot up and was in an endless reboot loop.
Just by taking the Seagate aside, everything is running smoothly and currently all my files are in their way back to the Drobo.
Thanks for coaching and advice.