Concern: ZFS Mirror issues (12.STABLE and firmware 19 .v. 20)

[Andriy Gapon]

On 09/04/2019 22:01, Karl Denninger wrote:
> the resilver JUST COMPLETED with no errors which means the ENTIRE DISK'S
> IN USE AREA was examined, compared, and blocks not on the "new member"
> or changed copied over.

I think that that's not entirely correct.
ZFS maintains something called DTL, a dirty-time log, for a missing / offlined /
removed device.  When the device re-appears and gets resilvered, ZFS walks only
those blocks that were born within the TXG range(s) when the device was missing.

In any case, I do not have an explanation for what you are seeing.

-- 
Andriy Gapon