No best solution available, because there’s no environment. NVMe SSD drives are a blast about performances, but… the fault tolerance is the same as an HDD or a SATA SSD.
i want to set PDC + MAIL SERVER + VPN + FILESERVER + NEXTCLOUD and we need fault tolerence with 3 HDDs as described above.
I want solution where i can set NS7 with fault tolerence.
IMVHO now not possibile with 3 mass storage devices.
You can use 2, used in software raid feature like the default setup.
Otherwise, you can install CentOS the way you like with NVMe and SATA drives, then install NethServer following documentation.
My hint: buy two 1tb SATA3 SSD, they seem pretty cheap during these days, even “not enterprise level” like Samsung 860 EVO. This will boost quite a lot disk throughput giving you opportunity to improve a lot performances.
Two 1TB SATA HDD will be useful in an NAS enclosure for backup or even with an old mainboard associated with a “NAS-Ready” distro.
For 250GB NVMe SSD drive you can always… boost up a desktop or a laptop.
There’s no sensible way to use all three of those devices in a single volume with Nethserver. A somewhat-sensible way to use them in a single server would be to install onto the SSD, then create a mirror of the two spinners and mount it at /var/lib/nethserver. All your data is stored with redundancy, but the OS itself isn’t.