WD1007V-SE2 controller -- 15Mb/s or not? Wren VI -- 650MB or 1.1GB?

[Stuart Lynne]

In article <1576 at redsox.bsw.com> campbell at redsox.bsw.com (Larry Campbell) writes:
>I'm using a CDC/Imprimis/Seagate Wren VI on a WD1007V ESDI controller.  The

>Now, if the WD1007V can't hack 54 sectors, I suspect it *certainly* can't
>hack 93.
>
>So here (finally) is my question.  Is the WD1007V a bozo controller, or am
>I doing something wrong?  Can I actually use 93 sectors/track on my drive,
>and if I need a new controller to do so, which controller will work?

NO, the problem is the overhead associated with each sector. The ESDI drive
doesn't particularily care how many bytes you associate with each sector.
You basically get a certain amount, for example 31,410 bytes on my XT-8760E.
And can you divide it up how you like. (So the maximum in theory for my
Maxtor is 61 512 bytes sectors.) 

Unfortunately the controller has overheads, so that it needs to use more
than 512. In the case of the 1007V, it can support up to 54 spt so the
overhead is something like 69 bytes (it needs 581 bytes per sector).

The 1007V actually will run and allow you to use 54spt. But unfortunately
the speed of the 1007V is such that it can't quite keep up so performance is
poor (one sector per revolution). If you reduce the speed by lowering the 
number of sectors per track to 53 it runs at full speed (full track per
revolution).

-- 
Stuart.Lynne at wimsey.bc.ca ubc-cs!van-bc!sl 604-937-7532(voice) 604-939-4768(fax)