Question about QNAP TR-004 Expansion Unit

If you already have a Qnap NAS, which is better, activating the raid "mechanically" on the back of the box and connecting it to the NAS or making a software RAID 5 via the NAS?

As described above, this is no problem. You only have to enter the new volume on the extension in the Plex. In the Plex view afterwards, everything appears as usual in your menu. Note: On the extension, if you have TV series, you have to label the folders differently than on the NAS so that they are read in correctly.

You must create your own RAID on the TR004. Note that it is not possible to expand the RAID, but everything must be deleted and rebuilt. My own goal was a JBOD with 3 disks to expand to 4 disks later if needed, which is also not possible.
Read the reviews at Digitec, especially Anonymus' "Works, is surprisingly inflexible".
The product page at QNAP (https://www.qnap.com/en...) describes various usage scenarios. The limitations are described in the small print.

You then have 2 raid systems. However, you can set this in Plex so that it can also access the 2 raid. When it is not in use, it switches to standby, but is also there immediately when you need it.