So I have this new setup using a Samsung EVO 850 as O/S disk and a pair of WD Enterprize Black as datadisks in a RAID1 configuration. All on a HP Z400. W3550, 12G RAM. Trying to define a defrag schedule, I discovered that I can only set "all" or "none" which is a bit annoying since SSD's should not need defrag. I wanted to include the two 1TB WD disks and exclude the SSD from scheduled defrags, but this seems not possible, The O/S disk system partition could be manually defragged byt the hidden partition that "needs to be defragmented" could not. Trying to do a manual defrag returned an error 0x 80070057. I wanted to do it just once and then leave it. There are some answers regarding this error on the internet, but none seems to deal with this specific problem.