On Apr 20, 2006, at 12:29 PM, Gill, Geoffrey L. wrote:
Why it is LTO2 capacity reads differently than 3590's. My 3590's report 40GB when filling and "at least" 40GB when full. K tapes read 20/40 and LTO2's 200/400. So why wouldn't it show at least 400? Is this a TSM, LTO or some other issue causing this?
Estimated Capacity is an arbitrary, settable number, principally to guide humans in an expectation of how much a given media may hold.
Is a tape reporting 215GB when full really holding more than that?
That is the amount of data which TSM wrote through the drive.
It also makes no sense if estimated capacity is 400GB, and the drive is capable of supporting that, it only reports 200.
Sure it does... The native capacity of LTO2 is 200 GB (plus or minus a tad, depending upon the actual length of the individual tape). Think of a tape as containing 200 billion cells, and no more: the tape is incapable of holding more units than that. If the incoming data is compressible, the drive can store a representation of that original data and use fewer "cells" doing it, and *effectively* store more data on the tape. Richard Sims
