Raid Card controller for FC System

Roger Heflin rogerheflin at gmail.com
Fri Mar 28 00:07:36 UTC 2008


Bill Davidsen wrote:
> Roger Heflin wrote:
> 
>> Yeah, the good controllers that give good speed are all PCI-X or PCI-e 
>> you just cannot get speed with PCI.
>>
> I will let you make your own determination of "good speed" here, but the 
> oldest and slowest PCI bus is 32 bits at 33MHz, or 127MB/s. The most 
> common is v2.1 spec, 64 bits at 66MHz, or 400-500MB/s actually 
> measurable at bus limits. So for most users, the disk is going to be a 
> bottleneck first.
> 
> It's something to be aware of before writing off bad performance as 
> "slow bus" limitations.
> 

That might be in the standard, but I can find no evidence that anyone actually 
implemented 66 Mhz without 64bit and none of the normal desktop boards have the 
longer 64 bit slots one them.   So unless one has one of the enterprise class 
boards (desktop or server) they probably have a limit of 127MB/s.

I checked both of my boards, and a couple of the new boards and none mention 
having 66 Mhz PCI slots, and at least one expensive one mentions having 33Mhz
PCI slots.

Have you actually seen a 66Mhz non-64bit slot?  And was it a normal desktop board?

                              Roger




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