@planet_jeroen, @robb : I feel my hardware short after reading your comments:
This is a Dell server R320 24 GB RAM and 4 SATA DISK 1 TB each.
The four disks in ZFS as RAID 10; and limited to 8GB the ZFS system.
options zfs zfs_arc_max=8589934592
Because it haven’t any load right now, I can’t see if I’ll hit a wall; need more tests before going to production. I really need to replace our old w2k server.
What I like is the idea of ZFS snapshots for safety upgrades in NS and peace of mind.
So, if I see that I only can have the NS in this hardware; I will give less RAM to NS, and extend the 8GB RAM for ZFS. I hope that I can have at least to VMs: 1 NS, and other one for a payroll system in windows, so I can take out another hardware at least.
Edit1: sadly, this system can’t hold more disks. Just more ram and hopefully bigger disks later.
Reading this guide avidly.