If you ask about DITTO - well in my understanding DITTO has no idea
about real BPI. How DITTO can measure length of the tape and number of
bytes written, especially when compression is turned on? Can DITTO
access number of metres of tape rewound from any counter in the drive?
I can be wrong, but I believe DITTO provides the value from some
table, rather than from measurement. I can be wrong here.
As for BPI, you are correct. There is no hardware query that provides
it. For our FATS/FATAR products, we depend on info from the various
vendors (various = 2) for the approximate BPI.
For tape length, 3480s had a fixed length cartridge. 3490Es had a
double length cart, but it provided a query to tell you what kind of
tape was mounted. For more modern systems, the queries have gotten
complex but they providea lot of info about the tape.
But for your second question, there is a way to get the compressed bytes
written and read on the tape. It works even back to 3480s with IDRC, so
we can calculate approximate tape length used, and estimate percentage
used.
--
Bruce A. Black
Senior Software Developer for FDR
Innovation Data Processing 973-890-7300
personal: [EMAIL PROTECTED]
sales info: [EMAIL PROTECTED]
tech support: [EMAIL PROTECTED]
web: www.innovationdp.fdr.com
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