> Darren New<dne### [at] sanrrcom>  wrote:
>> On 6/10/2011 10:52, Alain wrote:
>>> It also see a sectors, cylinders and heads count that don't have
>>> anything to do with the actual values.
>>
>> Yep. That's what I said. Of course the drive knows which sectors are where.
>> THe interfaces might not, and the OS can't see it, and that's exactly one
>> reason why people still use mainframes where important information like this
>> isn't hidden from the OS.
>>
>> --
>> Darren New, San Diego CA, USA (PST)
>>     "Coding without comments is like
>>      driving without turn signals."
>
> That's not quite true anymore, at least with IBM mainframes. That was true with
> the early IBM drives like the 3330, 3350, 3380, and 3390 drives.  But the last
> several generations of IBM disk drives have been raid devices.  The legacy 3390
> disk drive format is emulated by heavily cached controllers, backed by hi-speed
> scsi drives.  What appears to the mainframe as a cylinder is really data blocks
> spread across several scsi drives.  The model ds8100 I work with emulates about
> 1200 3390 virtual drives with a total capacity of 15TB.  The actual data is
> contained on a hundred or so 10000 RPM scsi drives.  All the time I once spent
> trying to optimize disk performance by placing system datasets at specific
> locations on the drives to minimize head movement is no longer necessary.
>
> Isaac.
>

All this talk makes me wonder... has there ever been a mainframe port of 
POV-Ray?

/Sorry for veering on-topic
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