I have a Synology 4-bay NAS (RS409RP+) with a RAID 5 installed on 4 hard disks. Now I need to upgrade the NAS to a bigger set of hard disks, and because these hard disks are 3TB each, I cannot use the normal RAID upgrade function. Of course I am going to make a backup and migrate the data over to the new disks, but I would like to keep the old disks functioning in the meantime, so if something goes wrong, I can reinsert the old four disks and continue as normal.
My question is, when I shutdown the Synology NAS and remove ALL of the disks, is it possible to re-insert them again later in the same order and will they still function normally?
Or does the NAS keep some information about the internal hard disks somewhere else (e.g. in the bios or an internal flash memory) and will it report that the raid has failed when I insert the old disks again? Or will it know that I have inserted some other disks in the meantime?
According to my understanding it shoud be save, but before I attempt this, I would like to know if someone has some definitive experience with this?