If your NAS is RAID 5 / RAID 6 configured, you can just stop Plex for a moment, hot swap the drive, get the rebuild started on the NAS, then restart Plex.
(Theoretically, you can pull the drive and let plex run but I’m always cautious)
That’s the beauty of RAID 5/6 or higher.
I have 12 drives - RAID 6 and except for physical access, I don’t need turn it off to get into it.
