WD Red HDD showing as SSD in Drobo 5D

Hello there…
Without checking changes in drives compatibilities I bought 5 new WD Red WD30EFAX 3TB to upgrade my WD Red WD20EFAX 2TB ones. Drives are reported as SSD by Drobo dashboard. I read some threads about this problem in other forum categories.
Just one question: will my data be safe anyway?

André Rombauts,

I believe the drives you have use Shingled Magnetic Recording (SMR) instead of Perpendicular Magnetic Recording (PMR). Their unique design might cause them to appear as SSD. Even though they are marketed for NAS use, their poor write performance will cause the drives to be “dropped” from the array and error out. I would return them if possible.

To avoid buying SMR drives in the future, you can either buy WD Red Plus drives or higher capacity like 8 TB and up


Thanks for your reply. I cannot return them: they have been installed in my Drobo…
I don’t need a higher capacity Drobo thus 3Tb drives are OK for me.
Note that this is not my main Drobo. It is my “old one” dating back to 2013. I’m using it as a backup drive. The main one is a 5D3 using WD30EFRX-68E HDDs. I couldn’t get the same drives so…


The Drobo 5D running 5 SMR WD30EFAX HDD hasn’t shown any r/w problems so far…


From most of the threads & posts I’ve read on the subject, the risk is that such problems show up during a rebuild after a changed or failed drive, when the unit becomes the busiest it’s likely to be, which is exactly when you don’t want problems.

When I upgraded my 5D from 2TB to 3TB WD30EFAX HDD I removed one by one the 5 drives and inserted the new ones. I encountered no problems during a process that extended over nearly 24 hours. How should have been reported the problems? Pop-up message? Hangup?


As I understand it the problems are poor performance (very slow rebuild times, think Gen 2 or worse levels) and/or randomly dropping out of the array during rebuilds and other heavy usage. I’m thinking you may have got lucky. You may or may not be as lucky next rebuild, It’s your data and your risk if you keep them in service. Personally & given it’s a known issue, I’d switch to conventional PMR disks, wipe the SMR ones & recover what value I could by listing them on an auction site or deploying them elsewhere.

Thanks. CMR drives are not OK either?
Anyway, this is a backup Drobo. My main Drobo a 5D2 is running 3TB CMR drives.


CMR (conventional magnetic recording) == PMR & would be just fine.