Why does unpartitioned Hitachi HDS5C3020 drive start consuming 50% more power 15 minutes after boot?
Solution 1:
Sounds very much like the drives are doing SMART scrubbing (automatic offline testing).
smartctl -a /dev/hdx
should confirm the configuration with:
Auto Offline Data Collection: Enabled.
Disable with:
smartctl --offlineauto=off /dev/hdx
It could be something else too...