I ran a scrub on my pool over the weekend and after it had completed I had numbers beside many of the drives in my pool, a few were triple digits below 150 and some were single digits below 20. The scrub said it completed with 2 errors. Should I be concerned? I am running ZFS under unRAID.
Non-zero numbers under the READ, WRITE and CKSUM columns of zpool status indicates that ZFS found errors when reading or writing to those disks. So yes, you should be at least a bit concerned.
100-150 would be very concerning to me. What kind of redundancy are you running on this pool?
Since there are many drives that are hit by this, could it be that you have another source of errors? backplaces, power supply, maybe bad RAM in the motherboard?