It also depends on the either the st.conf settings or what Sun has built 
into the driver. 
In st.conf there are 4 possible density settings coresponding to l,m,h and 
c however they can all be set to the same value or in an order that 
actually sets say the l device to compress. 
Now I have tested LT0-1 settings ( comparing the inbuilt driver to a wide 
variety of st.conf settings) and Suns' built in was as good as anything I 
could come up with. But from past experience they have been known to get 
things wrong - both Sun and Quantums original st.conf setting for DLT were 
not the best.

Which reminds me I must ask Sun to publish what their inbuilt drivers 
settings actually are.

On Thu, 6 Mar 2008 18:14:48 +0000, A Darren Dunham <ddunham AT TAOS DOT COM> 
wrote:

>On Thu, Mar 06, 2008 at 12:27:56PM -0500, Howard Martin wrote:
>> I think the hbn device will still compress you might get a bit more on
>> using just [mbn].
>
>It depends on the device.  LTO (and DLT) are explicit with the density
>settings.  So the c/u device is highest density with compression, while
>the h device is the same density without compression.  (and m is
>compression at a lower density with l being non-compressed at that same
>lower density).
>
>AIT devices don't have the explicit settings.  All devices have the same
>density configuration.  So I *think* (beware) that not using the c/u
>device is all you need to disable compression.  But I've never tried to
>test it.  (I'm using LTO at the moment and can't easily check AIT).
>
>--
>Darren Dunham                                           ddunham AT taos DOT com
>Senior Technical Consultant         TAOS            http://www.taos.com/
>Got some Dr Pepper?                           San Francisco, CA bay area
>         < This line left intentionally blank to confuse you. >
>
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