Re: Detecting failing drives - ZFS carries on regardless

I've just tested a batch of drives overnight by zeroing every block. One 
of the drives has averaged 4tps instead of 100+. FreeBSD has not faulted 
the drive. It hasn't even put an error on the console. It's never 
returned an error to dd. The SMART monitoring data on the drive says 
it's "OK". a CAM defects query returns "0 defects" (other than primary).

I've found someone else that seems to have noticed something similar.

https://forums.freebsd.org/threads/failing-sas-drive-not-removed-from-zfs-mirror.87781/

Looking at mode pages 1+7, I spotted "Verify Recovery Time Limit" was 
set to 65535. This is in milliseconds, but I wonder if 0xffff means 
infinite?