Replace drive on PR4100, does it need to be formatted/empty?

I’m about to replace one of the original disks on my PR4100 (wd red 2TB). I have a spare which I used in my windows PC. Do I need to format this disk before I put in the PR4100? Or will the OS take care of this as well.

Hi @kirre777,

Have you opened a Support Case? If not opened, for more information, please contact the WD Technical Support team for the best assistance and troubleshooting:

So I ended up just putting the disk in and then activated raid auto-rebuild. Took a few hours but everything is ok now.