DLTVS80 FORMAT

[Allan_24]

Hello,

Aside from Encoding technique and tape read/write speed designed that made DLTVS80 differs from other DLT's, what else can you share to me in terms of technical reasons that really explain for this kind of tape device?

Please fell free to comment, co'z this is more on references for those who really need to know the reason behind all this and your help is very appreciated.

By the way, is there anybody can tell me the differents between Run Length Limited RLL(1,7)over RLL(2,7)....(just disregard PRML for SDLT and LTO)


Regards,
@@,?

[David Ruska · Accepted solution]

Start with the easy one:
> By the way, is there anybody can tell me the differents between Run Length Limited RLL(1,7)over RLL(2,7)

Not much. The numbers specify the run length (1 or 2) and the run limit (7) in the encoding, which mixes clock signals with data. These specify the minimum spacing between reversals, and the maximum spacing between reversals. If you want to know more, look here:
http://www.storagereview.com/guide2000/ref/hdd/geom/dataRLL.html

> Aside from Encoding technique and tape read/write speed designed that made DLTVS80 differs from other DLT's, what else can you share to me in terms of technical reasons that really explain for this kind of tape device?

* DLT1/VS80 can only read DLT4000 format, whereas DLT drives are backwards read and write compatable with their predacessors.

* Transfer rate limited at 3MB/sec native, and the compression engine saturates at 6MB/sec (of the data compresses >2:1).

* Uses an MR head.

* Uses its own type of cleaning tape (not sure why it's differnt, but it must be less abrasive, as they recommend regular cleaning instead of cleaning only when the cleaning light comes on).

That's all I can think of, other than the spec differences. The drive was designed to be lower cost than a DLT drive. Benchmark was a partially owned subsidiary of Quantum when they the product was designed. Now Quantum fully owns Benchmark (and eliminated the Benchmark brand).

The VS line continues with the VS160. You can look at Quantum's drive roadmap:
http://www.quantum.com/am/products/dlt/technology_roadmap.htm

[Allan_24]

Hi David,

Thank you very much for you time to help me about this issue,

I just wondering if maybe that Encoding technique that designed for vs80 really affects the compatibility issue from other DLT format,particularly DLT8000(though it uses the same media which is DLTIV).Imagine the DLT80 or DLT8000 used RLL(2,7) while vs80 utilized RLL(1,7).

[David Ruska]

> I just wondering if maybe that Encoding technique that designed for vs80 really affects the compatibility issue from other DLT format,particularly DLT8000(though it uses the same media which is DLTIV).Imagine the DLT80 or DLT8000 used RLL(2,7) while vs80 utilized RLL(1,7).

I'm not sure why they changed to 1,7 for the DLT1/VS80. Perhaps the read channel has more margin with the MR head used. The DLT1/VS80 read channel has to do both 1,7 and 2,7 since it has backwards read support for DLT40.

Note that the VS160 change to PRML, so it needs to read 1,7 (VS80) and PRML.