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Home > Archive > Data Storage > March 2005 > Quantum Standards for Exceptional SDLT Tape Quality
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Quantum Standards for Exceptional SDLT Tape Quality
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| For DLT Type IV tape, we have a table published by Quantum that shows the
number of soft errors on each tape that would be considered each of the
following quality levels:
Exceptional
Good
Normal
High Error
Quantum publishes a table with these quality levels for soft read errors and
separately for soft write errors. We found this in the DLTTape for DOS
software manual.
Does Quantum have a similar table of quality levels for SDLT I and SDLT II
media?
--
Will
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| No. SDLT is far more complex, and there is no hard and fast rule
because servo errors come into play. For the magnetics, you can use the
same old limits (the low numbered counters in log pages 2 and 3) since
they're scaled relative to tape length, so they are independent of
capacity. For servo errors (0x8003 parameter), the count isn't valid,
it's the density of servo errors. The drive can tolerate thousands of
servo errors across the length of the tape if they are spread out, but
a few bunched closely together (e.g. from tape edge damage) can cause a
hard write error. Your best bet would be to make sure there are 0 (or
maybe 1) servo errors on new tapes, and then watch if the media
develops additional servo errors over time, of if one drive shows more
than others. DLTSage will do that (and more) for you, so watching for
Tape Alerts in operation is highly recommended.
Hope this helps,
Ralf-Peter
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