PCI-Express add in card

From PEL Wiki

I've come to believe that since we are doing comparisons between variations of the same systems, absolute performance is less important.

Therefore, I'm trying to enumerate the possibilities better than I have.

I found some interesting PCI-express cards that are geared toward networking applications.

If I accept the extra latency to the hard drive which I will incur, I could use a network hard drive and save myself from dealing with SATA.

PowerQUICC from freescale (MPC8548E) is a SOC which consists of a PCI-Express interface, PowerPC core, and some other peripherals. They are targeted to networked storage applications. Right now I'm looking for a development board which integrates the PowerQUICC processor with SATA, DDR, and possibly some SRAM. It seems like they have one, which is called PPCEVAL-CDS-8548, but the distributor knows nothing and Freescale hasn't responded to my inquiry yet.

Intel's Xscale processor is very similar. There is a board from IP Fabrics which is called the double espresso, with two Xscale processors, 1GB DDR, 16 MB QDR SRAM, and Gb ethernet. There's also a board from Intel that seems to have most of it.

It seems to me that if I bought one of those boards and a network disk such as the Maxtor Shared Storage, I could be up and running very quickly.

Using these cards means doing the address translation in software on a slower processor. This could be bad.

The PowerQUICC has a 36-bit address space, which I believe could be directly mapped so that it could serve requests from its RAM without software intervention, except when there is a page fault.

Another thing I could do is buy an FPGA which comes with the evaluation PCI-express core which is free as long as it is used on the board. It has a PCI-express slot which could be used for a SATA card. Then I could avoid buying a SATA core.

The question is "How much latency can we tolerate?"

The Hitech Global Board that we already ordered.