Adaptec 2940UW vs Atto ExpressPCI UL2D

[Tim Seufert]

On Wednesday, October 9, 2002, at 04:47  PM, Stefan Jeglinski wrote:

> Any caveats about use or performance comments regarding these two 
> cards? I currently have the 2940UW in a 9500 and it runs with Linux 
> fine. I'm going to attempt to install OSX on this box and am 
> suspicious that the Adaptec will flake out as per other reports. The 
> Atto card is a pull with Apple ROMs and I figure my chances with OSX 
> are better, but I don't want to compromise or break Linux either.
>
> If in Linux they both work fine, are there any performance differences 
> that anyone knows about?

For a fairly long time I used an ExpressPCI PSC (the Atto equivalent of 
the 2940UW) with an IBM UltraStar 9ES under YDL.  The 9ES was the Linux 
root partition.  Never had a single problem with the controller, though 
the disk eventually developed mechanical problems.  (This was in a 
Beige G3, BTW.)

As for performance, the 2940UW is a single channel Ultra/Wide 
controller (40 MB/s), while the UL2D is a dual channel Ultra2/Wide 
controller (80 MB/s * 2).  So I think it's safe to say that the UL2D is 
faster.  :)  In a 9500, either channel by itself could just about 
saturate the PCI bus (the 9500 class machines can achieve around 80 
MB/s PCI throughput).  (Realistically speaking you'll be limited more 
by your disks, of course.)

The only danger I can see is that the UL2D is a relatively recent card 
and I have heard that sometimes modern PCI devices don't work well with 
Apple's old PCI controllers (the 9500 was Apple's first generation PCI 
machine).