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Ultra2 SCSI Raid - 32bit PCI vs 64bit PCI performance - HELP!!!!!

S

Stealth

Senior member
I recently purchased a 2 channel Ultra2 SCSI Raid controller (64-bit, but will also fit in a 32-bit PCI slot) because I couldn't afford an Ultra160 SCSI Raid controller at the time. I have (3) Ultra160 18.4 GB 15,000 RPM (got a really good deal on them) hooked up to it. I know that I'm not using the full potential of the Ultra160 HDD's because of the Ultra2 SCSI RAID controller bottleneck. I was wondering if I should get a motherboard with a 64-bit PCI slot to hook up the Ultra2 SCSI RAID card. I know that if I had purchased the Ultra160 card, then it would be a must because of the increased performance, but would there be a significant performance spike if I were to stick the Ultra2 card in a 64-bit PCI slot rather than a 32-bit slot? Any numbers to back it up?

 
What is the make and model of your HBA?

You MUST use both channels to see the full potential of the card. Most likely it's a 64bit 33MHz HBA which will give you a (max) xfer of 266 MB/S.

IME, 64bit HBA perform considerably worse in 32bit slots. Nowhere near the potential 133 MB/S of pci. 80 is typical. Your results could be even worse with a VIA based chipset. When the adapters are in 64bit slots that changes as they have the breathing room they were designed for. 32bit compatibility just guarantees that the product will work just not at optimal performance.

Cheers!
 
I have the:

Mylex eXtremeRAID 1100
64Bit 3-Channel Ultra2 SCSI RAID Controller /64MB Cache Memory and Battery Backup Unit
233Mhz RISC StrongARM processor

I was planning to use it on an ASUS TR-DLS board which I believe has the ServerWorks LE chipset, but the board blew out, so I need to look for another one. Is it necessary that I look for another board with a 64 bit PCI slot?
 
Any suggestions on a dual PIII Tualatin with a 64-bit PCI slot that would fit in a 1U chassis? Thanks alot!
 
😕 The Mylex Extreme RAID is really 32 bit compatable? Heard it was faster in 64 bit slot than the Adaptec 2100S, U160 RAID (U160 vs U2). Have been doing a lot of reading and researching on the PCI "bottleneck". Got into it because of my 3 VIA chipset MBs. Have looked at the S2460 dual motherboard (as a single CPU), as it is one of the few afordable boards with 64 bit PCI. What worries me is, unless the PCI slots are really separate busses, the buss will be more than saturated by a gigabit NIC and SCSI RAIDs. Have never found a good non-super-geek discussion on the subject of PCI and throughput. Have always wondered why motherboard makers were slow to adopt 64 bit PCI. Hope this is enough to get a good discourse going. 🙂
 
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