# AHA-2940UW and multiple cd-roms speed



## big_girl (Aug 9, 2010)

Hi all,

I have an adaptec aha-2940UW PCI card (advertised 40mb/s but I've only connected it to single cd-roms) and would like to connect 3 scsi cd-roms to it -- two plextor ultra max scsi cd-rom drives (px-40tsuwi) to the 68pin port, and another ultra max 40 wide 50 pin drive (px40-tsi) to it's 50 pin internal port. The card can support at least a dozen devices. I have a raidz2 zfs which I can write to at ~36mb/s in a pretty fast multicore box.

I'd like to be able to use all 3 drives at once (with no speed loss), extract cd audio using cdparanoia, and write it to the zfs. If anyone has a similar setup I would love to hear if the 3 drives can all hit their max speed while all extracting audio at the same time.

Using the calcs from http://www.milosoftware.com/mike/scsi_ide.html I get this -- since the two px-40tsuwi drives can sustain 6mb/s and burst 40mb/s, and the other drive can sustain 6mb/s and burst 20mb/s, the calculation is (?)

6/40 + 6/40 + 6/20 = 24/40 

and that is way less than one, which makes me think the one card can handle all three drives sending data at top speed. 

I'm running 8 stable 64bit..

Any help would be really appreciated before I start this experiment.. 

Thanks in advance,
-bg


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## big_girl (Aug 31, 2010)

yes, plenty of bandwidth for this no problemo..


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