Restoring Data from DAT72 to DDS4 tapes

Hi Guys, I have 2 servers

1.IBM System x3650 with Dat72 Tape drive
2. IBM xSeries 235 Server with DDS-4 Tape drive

i'm using DDS-4 tapes to be supported by both of them
the problem is i can make a backup on the dds-4 tape from the DAT72 Tape drive with no problem but i can't restore it on the DDS-4 Tape drive which shows that the tape is empty but i checked it on the DAT72 Tape drive and i found the data there....
both of these servers are running windows Server 2003 Enterprise Edition , i can't find any special settings to try n error in the device manager

can anyone tell me what iam missing to make this work for both servers.
medoamerAsked:
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slemmesmiCommented:
Dear medoamer,

it could sound from your problem description that the tape offset setting of the drives are different.
Try to see if you can find this/such setting on the '1' and set accordingly on your '2'.
I do assume you're using the same backup/restore software on '1' and '2'?

Kind regards,
Soren
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Duncan MeyersCommented:
Here's why the tapes written on the DAT 72 can't be read by the DDS-4:

"DAT-72 tapes are 170m long and data is written in narrower tracks, again increasing data density, enabling tapes to hold 80% more data than DDS-4 tapes. " - the emphasis is mine.

(from http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=lpg50457&locale=en_US&taskId=101&prodSeriesId=81997&prodTypeId=12169)

In short, tapes written on the DDS4 can be read on the DAT72, but not vice-versa. Wikipedia has this to say: "Backward compatibility between newer drives and older tapes is not  assured." (http://en.wikipedia.org/wiki/DDS-4)

So - this behaviour is expected. The tapes DDS-4 tapes written by the DAT72 drive can't be read on the DDS-4 drive
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medoamerAuthor Commented:
I'm using Windows NTBackup on both servers .... is there an advanced Configurations menu somewhere?
i can't find any thing about that "tape offset setting"
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Duncan MeyersCommented:
The problem lies with the construction of the tape drives - not the configuration of the backup software. Backward compatibility for tape drives means that a newer drive can read (and write) an older tape format but the DDS-4 is simply incapable of reading the tapes created by the DAT-72 drive as the data is written in a narrower track.
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medoamerAuthor Commented:
So isn't there any way to make this work in windows .... i faced the same problem with the same devices but on IBM AIX 5.2 system but it has been solved by changing Block-size & Density  parameters
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medoamerAuthor Commented:
i found out that only a portion of the backed-up data was readable on the IBM AIX 5.1 ... so i'll try and change the Tape Drive with another DAT72 Drive
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Duncan MeyersCommented:
Thanks! Glad I could help.
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