Does ZFS replace the need for hardware/software RAID?
Solution 1:
Yes, ZFS doesn't need hardware raid and is actually better when used without it.
It is able to provide partial data protection even with a single device when configured to use ditto blocks but of course won't resist a full disk failure in that case.
You can use it in a mirror configuration (two devices or more) or a RAIDZ one (three devices or more) to survive failures. RAID-Z2 and RAID-Z3 provide 2 and 3 concurrent device failures protection.