On Friday 24 January 2003 08:53, Martin Oehler wrote:
>Hi!
>
>I've run tapetype on a LTO Ultrium drive and some questions
> concerning the results. The tapetype test has been made twice,
> once with hardware compression (HC) turned on (by mistake) and
> once with  HC turned off.
>
>The OS is Linux and 'mt' is telling me actually:
># mt -f /dev/nst0 datcompression 1
>Compression off.

That *should* have turned it on, if indeed mt knows anything about 
this drives foibles.

>The results of the first run (with HC) were:
>
>define tapetype unknown-tapetype {
>    comment "just produced by tapetype program"
>    length 104261 mbytes
>    filemark 545 kbytes
>    speed 1601 kps
>
>}
>
>Results without HC:
>
>define tapetype unknown-tapetype {
>    comment "just produced by tapetype program"
>    length 104302 mbytes
>    filemark 547 kbytes
>    speed 1603 kps
>}
>
>Why is the length the same? Seems like switching the compression
> modes with mt is not working.

It was still on?  You didn't say that you had turned it back off 
above.  Maybe this drive has a compression scheme like the DDS 
drives do, whereby it records the compression status in a hidden 
header, and resets it to match that tape when the tape is next 
scanned at insertion.  In which case see my rough outline of what 
it takes to turn those flags off, in a previous message earlier 
today.

>Additionally, I can't understand why the speed is that slow. The
> drive should write about 15 MB/sec without HC. Is it possible to
> ignore the measured speed and use the one from the datasheet of
> the tape?

How fast is the interface?  Maybe it can't to 15 megs a second, 
older scsi stuff was hard pressed to do 5 megs, often less.  Much 
less.

>
>The used amanda version is amanda-2.4.3 .

Which snapshot?  It should have a date string after the 2.4.3.

>Thanks in advance for your help,
>Martin Öhler

-- 
Cheers, Gene
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