EasyGoing1
Dabbler
- Joined
- Nov 5, 2021
- Messages
- 42
When installing TrueNAS on fresh hardware (the drives have never been used before), I'm curious about how ZFS configures a new drive pool when you start with two drives vs. three drives.
And my question is rooted in my prior experience with RAID, wherein a two-drive scenario, if you want redundancy, you have to mirror the drives, but if you have at least three drives, then you can move to a RAID-5 which, of course, mitigates a single loss among all three drives.
If one were to start their TrueNAS with only two drives (assume a separate drive runs the OS and is not part of the pool), does ZFS set them up as a mirror? Or does it implement some other algorithm such that adding a third drive causes ZFS to be able to merge the data from the first two and spread the load over all three so that you have a true three drive scenario where you could lose any one of the three and still not lose data? Or would you have to back the data up, and then re-create your ZFS with all three drives then restore the data?
And my question is rooted in my prior experience with RAID, wherein a two-drive scenario, if you want redundancy, you have to mirror the drives, but if you have at least three drives, then you can move to a RAID-5 which, of course, mitigates a single loss among all three drives.
If one were to start their TrueNAS with only two drives (assume a separate drive runs the OS and is not part of the pool), does ZFS set them up as a mirror? Or does it implement some other algorithm such that adding a third drive causes ZFS to be able to merge the data from the first two and spread the load over all three so that you have a true three drive scenario where you could lose any one of the three and still not lose data? Or would you have to back the data up, and then re-create your ZFS with all three drives then restore the data?