Hi,
Please check the media set propertiesof the target media set.
Verify whether there any active alerts in the "Alerts" tab.
Please refer to the following document
When performing a backup operation, a device "request to space to end of data" or "semaphore timeout" or a "SCSI bus timeout" error is generated.
http://support.veritas.com/docs/190598
Hope this helps.
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