Re: from PCI framegrabber to PCI raid

[Neal Palmer <neal@dinigroup.com>]

Geert,

  Good luck.  But here is a suggestion.

  Something else that other people haven't mentioned yet is the
possibility of changing to a 64-bit PCI bus with the use of PCI2PCI
bridges (64-bit PCI motherboard required).  You can double the bandwidth
to your memory if you put your RAID behind a P2P bridge, and your frame
grabbers behind a different P2P bridge.  There are some drawbacks to this
method, but you might consider it as a possibility.

  The bridges will translate the 32-bit bus to/from a 64-bit bus, and
should hopefully give you enough bandwidth to spare on the motherboard's
PCI bus. It will cost you a bunch of latency when the RAID is reading from
main memory, but that can't be avoided (unless you find a 64-bit RAID
card, and can remove it's bridge).  Write transactions won't be hurt by
having the P2P bridge between the framegrabber and main memory.

-- Neal

On Tue, 4 Apr 2000, Geert Bellens wrote:

> Hello, 
> 
> I have an IDE RAID which is connected via the PCI bus.
> I have also 2 framegrabbers. I'd like to capture real time video (2 x
> 27Mb/s) to my RAID (max transferrate ~ 70 MB/s).
> 
> I haven't tried it yet. But I suppose it should work.
> 
> Is it however possible to move the video stream directly to the raid
> without passing the system memory ?
> Because if you use the PCI bus to pass the RAM and vice versa than the
> bandwith of the PCI bus is divided in half.
> 
> 
> Best Regards,
> 
> Geert
> 

-- Neal Palmer

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