Data Corruption Errors

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.