Suddenly high IO on File transfer operations

Been using the EX2 ultra for quite a few weeks. Configured Raid1, connected device to my AD, created shares and one ISCSI Taget. Everything went fine and i had file transfer speeds using SMB/CIFS at around 75 to 120 MBit/s.

No additional apps at all are installed

Suddenly, without any configuration change, the performance degrade massively. I’m now happy to get 4.5 MBit/s and additionally the transfer sometimes stops completely. CPU load is shown to be very high for a few secs. top on the console shows up to 99% io while the CPU itself is more or less idle.

What I did so far:
Reset the device to system defaults.
Restored configuration–>no change
Rebuild the RAID1–>no change

I do not have the slightest idea what may cause the problem and how it may be fixed and I am thankful for any suggestion.

Do you have cloud services enabled?

It sounds like the unit is indexing. . . . which does much to lobotmize units while the indexing runs (can be Days or even weeks depending on how much data you have)

That was my first thought as well but unfortunately no luck. I’ve never enabled it, did not even create an account for cloud access. I also do not use any media server like Twonky or Plex.

Is it possible that, however, the indexing service has started itself without any interaction?