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SATA raid over 2 discreet PCI ?

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February 6, 2005 1:15:11 AM

I am concerned over the bottle neck in data transmission via standard PCI 33MHZ/ 32 bit. It appears to be a real limiting factor
when considering SATA raids, especially with the faster data transmission of the new10,000 rpm drives. ( see www.tweakers.net/reviews/432/6 ) Does anyone know if it is possible to use two seperate SATA controller cards in their own PCI slots in the opperation of a raid 0 (striped)?

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February 6, 2005 2:21:56 AM

I think you'd end up still capped at 133MB/s. If you could go PCI-Express it would help.

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February 6, 2005 4:07:37 AM

133mb/s is plenty fast lol. You would be hard pressed to get those speeds even with 2 sata raptors. I get about 90mb/s w/ my 36.7gb raptors in raid0 and that loads things pretty damned fast :) 
Don't have a heartattack over the limits of the PCI bus. It is fast enough for most purposes.

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February 6, 2005 4:27:13 AM

When the article mentions using seperate buses they are refering to server motherboards with one regular PCI bus and one PCI-X bus.

All the PCI slots share the same bus and share the same bandwidth, which contrary to what is stated in that article happens to be 127.2 MB/s not 133 MB/s!

Its a common error, but a professional writing an article should know better, the "M" in Mhz is 1000*1000 while the "M" in MB is 1024*1024.

I mention this because 2 74 GB Raptors in RAID 0 on a Via 8237 SATA controller average 129.5 MB/s, which is higher than the PCI bus's theoretical bandwidth.

Which means motherboard SATA raid is currently faster than any 32 bit 33 mhz PCI card ever can be.

PCI-X buses have double the speed and double the bus width resulting in 508.6 MB/s. No bottle neck there, but again many slots, one shared bus.

PCI-e is point to point, with each slot having one or more "lane" all to itself. Each lane if I remember correctly can handle about 2.5 Gbps (about 312 MB/s) in each direction. Not 100% about this figure.

Are there any PCI-e RAID cards yet?
February 7, 2005 4:31:57 PM

thank you ALL for the info.
Everybody was great

d
February 7, 2005 4:34:17 PM

thank you Folken

Man, that is quite a system you have there

d
!