The zpool status command also shows whether any known errors are associated with the pool. These errors might have been found during disk scrubbing or during normal operation. ZFS maintains a persistent log of all data errors associated with the pool. This log is rotated whenever a complete scrub of the system finishes.
Data corruption errors are always fatal. Their presence indicates that at least one application experienced an I/O error due to corrupt data within the pool. Device errors within a redundant pool do not result in data corruption and are not recorded as part of this log. By default, only the number of errors found is displayed. A complete list of errors and their specifics can be found by using the zpool status -v option. For example:
# zpool status -v pool: tank state: UNAVAIL status: One or more devices are faulted in response to IO failures. action: Make sure the affected devices are connected, then run 'zpool clear'. see: http://www.sun.com/msg/ZFS-8000-HC scrub: scrub completed after 0h0m with 0 errors on Tue Sep 1 09:51:01 2009 config: NAME STATE READ WRITE CKSUM tank UNAVAIL 0 0 0 insufficient replicas c1t0d0 ONLINE 0 0 0 c1t1d0 UNAVAIL 4 1 0 cannot open errors: Permanent errors have been detected in the following files: /tank/data/aaa /tank/data/bbb /tank/data/ccc
A similar message is also displayed by fmd on the system console and the /var/adm/messages file. These messages can also be tracked by using the fmdump command.
For more information about interpreting data corruption errors, see Identifying the Type of Data Corruption.