My drobo 5N does go into standby mode (LEDs dim and HDDs spin down) but fan always keeps running at some minimum speed.
I noticed that when I had no Apps installed, but now I have NFS installed and that did not affect my drobo 5N going into standby. I don’t think there is some process that is making requests to my drobo 5N and therefore preventing standby mode…
I don’t know… if the NFS shares are mounted then basically any access, if even it is to read metadata such as the last access time will cause a network request, keeping the 5N awake and possibly the disks as well.
Also, are you sure you don’t have other network devices (WD TV Live, SmartTV, etc) browsing your network behind your back and accessing the 5N using SMB on their own?
Mind you, that is not to say that the 5N will actually turn the fan off at some point. To be honest with you I never noticed mine going off, but then again I can’t even hear its fan next to the FS.
When no apps are running, the 5N will spin down and lights dim, but the fan will never stop completely (although it’s very close to silent). With DroboApps it’s a bit of a crapshoot - the vast majority ping the diskpack for something, and thus as soon as you load a few you can forget about it ever spinning down. Thankfully the noise level is much lower than the old FS.