cam status ATA status error

Hello,

I've been experiencing some problems with my Freenas server. When I run dmesg from the shell then I see a lot of cam status ATA status errors which I don't know what they mean. Here is a screenshot of it when it occured again. It does not always occur:



I have the following hardware:

HP Microserver Gen8
16GB ECC RAM
4x4TB WD RED NAS drives (which I bought new, 2,5 weeks ago and replaces all my previous drives which were 4x2TB drives)...

cam status ATA status error