On which HDD is it better to install Windows Server?

Question

Windows Server

Good afternoon! There is a need to assemble a small server (a file dump + a couple of not very resource-intensive software)
The question arose about installing a Windows server, namely, what is the best way to proceed
: file storage.
2. Buy 4 HDDs for file storage, assemble in Raid 1 + Buy 2 HDDs (smaller) for OS, assemble them in the second Raid 1. It will turn out 2 independent raids (everything is as I understand it?)
3. What are your options? Direct on the right path :)
Will the reliability of the System suffer greatly if both the File Storage and the OS are on the same disks?

Answer 1

Under OS 2 SSD (in the case of daily backups and non-critical downtime, you can have one), under the rest of the HDD.

Answer 2

As an option, a flash drive with a hypervisor and 4 screws for raid 10