More Streaming device questions

Tim Jones tjmac at tolisgroup.com
Wed Aug 25 10:01:22 PDT 2004


* From the T10 Reflector (t10 at t10.org), posted by:
* Tim Jones <tjmac at tolisgroup.com>
*
I suspect that this should cause an ILI since the fixed bit changes the 
meaning of the transfer length field (1 = Blocks, 0 = Bytes).  But, 
since the tape drivers have to actually control the writing (rather 
than a user app - disclaimer: on Unix systems), the driver should be 
aware of the state of the fixed condition and modify its CDB 
accordingly.

Tim
--
Tim Jones					tjmac at tolisgroup.com

On Aug 25, 2004, at 3:35 AM, Burn Alting wrote:

> * From the T10 Reflector (t10 at t10.org), posted by:
> * Burn Alting <burn at goldweb.com.au>
> *
> Yet more questions.
>
> When I start my tape target, I set the logical block size to a default
> value.
>
> For my block limits, I set my minimum block length to 512 and my 
> maximum
> to some large multiple of 512 bytes and since I want all IO in 512-byte
> quantities, I set the granularity field to be 9 (ie 2^9 = 512).
>
> If I want to perform IO in variable block mode, am I required to first
> set the logical block size (via a Mode Select changing the Block Length
> field in the Mode Parameter Block Descriptor) to zero and then issue my
> Read or Write commands with the fixed bit set to zero and the transfer
> length to be the number of bytes I want to transfer?
>
> If this is the case, ie I have set the logical block size to 0, what
> happens if a read or write command has it's fixed bit set to 1?
>
> Regards and thanks to all those who have been replying to my questions.
>
> Burn
>
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