gtar compare

[Fanguang Meng]

I have software to write data to the dlt tape, and then use gtar -d -b 512 -f /dev/dlt1 to validate the data. Everything is going fine util it reaches the file number 110, the tape rewind back to file number 55 -- half of 110.
Another example is at number 82 and look for file 41 on disk. Can anybody help to figure out what's happening.

Thanks very much.
FanG