Questions about Icy Box Ib-Rd3621u3

It can also be different disk sizes, even with RAID1. With RAID1, the smaller disk would simply determine the RAID size and the space of the larger disk would be lost and remain unused.

This is normal. Either the box has to be switched on and off manually via the switch on the back or you plug the power supply unit into a power bar with a switch and thus switch off the PC and the box. Of course, you could also use a power bar with a master socket. These automatically switch off all other connections as soon as the master (ideally the PC) no longer consumes power.

This device can be used for this, it is a Synology NAS with 5 drive bays. You can install 5 hard disks of any size and then set up these hard disks as a so-called RAID0 (this is a combination of all 5 disks, but without hardware failure protection), whereby if one disk fails the whole array is destroyed or you can set up 5 hard disks as RAID5 (then 4 disks are used for the disk array and one disk is subtracted).(4 disks are then used for the disk array and one disk is then subtracted for the parity information, whereby this information is written distributed on all disks, but in RAID5 you do not have 5 x 10 TB available but 4 x 10TB), whereby if one disk fails, you can still see the whole array online and simply have to replace the broken disk. Synology DS1522+ (0 TB) If even more space is needed, there are also Synology NAS servers that have 6 or 8 bays: Synology DS1621+ (0 TB) Synology DS1821+ (0 TB) With more drive bays, you can also choose smaller disks to create a large disk array.

https://raidsonic-static-content.s3.eu-central-1.amazonaws.com/IcyBox/Files/datasheet_IB-RD3621_e.pdf

No, to my knowledge the RAID always exists on the respective controller.

If the unit itself shuts down, the hard drives are still usable. If you had configured the hard disks as a raid, you must have a suitable new raid controller to access the data again. Regardless, you could reformat the disks and use them as you wish. In that case, however, you would have a complete loss of data.