Hello,
What drivers are you using for the device? The Veritas drivers or the manufacturer drivers?
Check out the steps mentione din the technotes given below:
Title: Device I/O error occurs during the verify portion of a backup operation with Backup Exec
http://support.veritas.com/docs/191087
Title: The error message "Error on a request to space to end of data. The request could not be performed because of an I/O error" is reported in Backup Exec 7.x, 8.x, 9.x, or 10.0 when attempting any media operation.
http://support.veritas.com/docs/191694
Hope this helps. If the problem persists, revert with details on the exact error message. Also check for errors in the event logs.
Note : If we do not receive your reply within two business days, this post would be marked ‘assumed answered’ and would be moved to ‘answered questions’ pool.
Regards.