ZFS [Solved] Understanding warning ZFS-8000-9P

H

homeadm

I received ZFS-8000-9P due to single checksum error. This is a single disk pool. Why do I get the message "Applications are not affected"? If there is no redundancy, error cannot be fixed, so applications should be affected. Where's the trick?
Full message:

Bash: 
# zpool status
  pool: rpool
 state: ONLINE
status: One or more devices has experienced an unrecoverable error.  An
        attempt was made to correct the error.  Applications are unaffected.
action: Determine if the device needs to be replaced, and clear the errors
        using 'zpool clear' or replace the device with 'zpool replace'.
   see: http://www.sun.com/msg/ZFS-8000-9P
 scan: scrub repaired 0 in 0h10m with 0 errors on Sat Feb 10 03:48:29 2024
config:

        NAME        STATE     READ WRITE CKSUM
        rpool       ONLINE       0     0     0
          c0d0s0    ONLINE       0     0     1

errors: No known data errors

Now, the warning has disappeared by itself.
 
Yes, it can be confusing: The payload (“application data”) is stored only once, but file system metadata, like the pointers to allocated blocks, is stored redundantly with checksums and what‑not. The super‑important superblock (or the ZFS equivalent) is stored several times on disk (at the beginning, at the end, maybe somewhere in the middle, too, I don’t know all the details by heart), so the data can still be read.​
 
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