TOS 4.2.39 to TOS 5.* - Existing RAIDs?

[V8Triker]

I am about to embark on a TOS 4.2.39 to TOS 5.* reinstallation on my F5-221
I currently have a RAID5 and RAID 1 volumes.

I appreciate that the RAID 5 will need to be formatted and freshly installed.
But, once that is done, can I put my RAID 1 disks back in, and will they be recognised with all the data intact?

[TMroy]

There is a update path from TOS 4.x to TOS 5.x, why you need to reinstall it? if you boot a TNAS device contains two systems, there may be conflict.

[V8Triker]

There is a update path from TOS 4.x to TOS 5.x, why you need to reinstall it? if you boot a TNAS device contains two systems, there may be conflict.

I thought TOS 5.x requires an 8Gb system partition, whereas TOS 4.x has a 2Gb partition. Re-installation is the recommended approach?

Terramaster really put the OS on both volumes?
The initial install was done with the RAID 5. The RAID 1 was added at a later date.
So, I could take my RAID 5 out and boot of the RAID 1, or take the RAID 1 out and still boot off the RAID 5.
Seems a bit crazy, to be honest.