Just had a server crash this morning.

The clustered pool refused to mount on any server (it would deactivate
and go comatose).

The error on the server was:

NSS-3.00-5001: Pool SERVER/POOL is being deactivated.
An I/O error (-1(zfsSuperBlk.c[2065])) at block 123230210(file block
123230210)(ZID 0) has compromised pool integrity.

I ran nss /poolverify.

After an hour or so it finished and when I hit F1 for the errors it said
NO warning and NO ERRORS.

Then I was able to mount the pool and online the resource.

I was under the impression that verify never actually wrote anything, so
I'm wondering how it "fixed" anything.

And if it did fix anything then why did it report no errors or warnings,
yet NSS refused to mount the pool?