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MB based RAID slower than PCI-E based RAID?

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January 25, 2007 4:23:12 PM

Currently I have 2 250GB drives in a RAID 0. The performance increase is substantial and I was thinking about adding another 2 drives to it to further increase performance and storage, being as I have the extra drives laying around anyways.

But I remember reading on here awhile ago (> 6months) about how MB RAID solutions inherently have a lower speed limit than PCI-E RAID because of the respective buses they operate on. The poster claimed that for this reason, there is no point in putting more than 2 drives on a RAID 0 MB bus because it would reach the speed limit and not improve performance, only storage. In order to maximize the speed available with 3 or more drives in RAID 0, you need to use a PCI-E RAID controller card. The guy had some math to prove it and really seemed to know what he was talking about. But I haven't been able to find that post again. Can anyone back this up? Does anyone have any experience with this?

Thanks
Eric
January 25, 2007 4:50:27 PM

Quote:
Currently I have 2 250GB drives in a RAID 0. The performance increase is substantial and I was thinking about adding another 2 drives to it to further increase performance and storage, being as I have the extra drives laying around anyways.

But I remember reading on here awhile ago (> 6months) about how MB RAID solutions inherently have a lower speed limit than PCI-E RAID because of the respective buses they operate on. The poster claimed that for this reason, there is no point in putting more than 2 drives on a RAID 0 MB bus because it would reach the speed limit and not improve performance, only storage. In order to maximize the speed available with 3 or more drives in RAID 0, you need to use a PCI-E RAID controller card. The guy had some math to prove it and really seemed to know what he was talking about. But I haven't been able to find that post again. Can anyone back this up? Does anyone have any experience with this?

Thanks
Eric


Because you are dealing with two drives only you are not likely reach your bandwidth limit up and down the pipes. However with a PCI-e interface allows more bandwidth up and down the pipe with an average of 2 GB/sec peak if you are using simplex. And 4 GB/sec peak using duel simplex bandwidth. You also get COD and NVRAM, large cache writeback and through options for redundancy. Onboard devices use more local resources to handle your Disk instructions. PCI cards leverage all those instructions with cache\ram and dedicated onboard CPUs. It doesn't seem that your going to run into this problem with a RAID0:Two disk array.
January 25, 2007 4:50:27 PM

So I tried using that "Search" feature everyone keeps talking about..... and I found this: Thread

And this: Thread

So I guess there is a bottleneck. Anyone notice a significant difference using a controller vs. on-board RAID 0 with 3 or more drives?

Eric
Related resources
January 25, 2007 4:53:39 PM

Quote:
So I tried using that "Search" feature everyone keeps talking about..... and I found this: Thread

And this: Thread

So I guess there is a bottleneck. Anyone notice a significant difference using a controller vs. on-board RAID 0 with 3 or more drives?

Eric


I have no real numbers, but I went from a u320 raid 0 on a PCI 32bit platfrom to a 64bit PCI -e 8x platform and doubled every HD bench.

Here is an older article on the subject. CLICKY
January 25, 2007 4:54:25 PM

Quote:
Because you are dealing with two drives only you are not likely reach your bandwidth limit up and down the pipes. However with a PCI-e interface allows more bandwidth up and down the pipe with an average of 2 GB/sec peak if you are using simplex. And 4 GB/sec peak using duel simplex bandwidth. You also get COD and NVRAM, large cache writeback and through options for redundancy. Onboard devices use more local resources to handle your Disk instructions. PCI cards leverage all those instructions with cache\ram and dedicated onboard CPUs. It doesn't seem that your going to run into this problem with a RAID0:Two disk array.


Right, I only have 2 drives at the moment, but like I said, I was planning on adding another 2. So I'm wondering if the on-board NVRAID RAID 0 can handle it, or if I should grab a PCI-E controller.

Eric
January 25, 2007 4:58:03 PM

And can I boot from a PCI-E-based RAID?
January 25, 2007 5:15:15 PM

Quote:
And can I boot from a PCI-E-based RAID?


Personally, Go PCI-e (at least 8x with some type on onboard cache). Yes, most all new mobos should be able to see disk controller cards to work the MBR or GRUB.
January 25, 2007 5:21:20 PM

Cool thanks.
!