A reverse lookup failed due to media errors.
Use your host application to validate the data on the volume. After you have located the hard disk errors, restore the missing data from backup.
If the volume is mirrored, and the affected volume is one of the copies, you can use the repairvdiskcopy command with the -validate flag to compare the faulty copy to the good one. Use the -resync option to restore the data from the good copy to the faulty one.