I’m am preparing to build my first own NAS-Server and would like it to have double redundancy, as in that two of the four Drives can fail before Data loss occurs.
When reading up on ZFS, i learned that one drive can be considered a spare, which means that upon a drive failing, the spare will automatically replace it until you replaced the fail drive. So technically you can also survive 2 Drive fails just like with Raidz2.
The capacity would be the same either way.
Based on what i read i would say the advantages are as follows:
Raidz1 + Spare:
The spare would be inactive most of the time, leading to a longer life and consequently a lower likelihood of two drives failing at the same time.
Raidz2:
More speed.
Is that about correct ? Or are there other advantages/disadvantages?