Speed Drobo FS

Hello every one ,

I have a problem with the transfer speed between my iMac 27" and the Drobo .
The Drobo is linked to the Mac by means of a gigabit switch (directly attached to the ethernet cable)
In the Drobo are 4 1 TB Sata Samsung fitted.

In the beginning transfer speed seems OK , but after a while it drops dramatically low (to speeds at around 300KB/s).
I reduced local network activity to the lowest possible , but this problem keeps recurring.

What might be the cause of this ?

If your usage is high, 90% or more, it will dramatically affect performance.
Or, you might have failing drives…