On Wed, Jul 02, 2008 at 01:08:04PM -0500, David Lethe wrote: > Everything is a potential bottleneck. As I am under NDA with most > of the controller vendors, then I can not provide specifics, but > suffice to say that certain cards with certain chipsets will max > out at well under published speeds. Heck, you could attach > solid-state disks with random I/O access time in the nanosecond > range and still only get 150MB/sec out of certain controllers, > even on a PCIe X 16 bus. Short of signing an NDA, how would one go about determining which chipsets are least likely to be a bottleneck? I'm interested in building an NFS server with a Linux software RAID-5 data store. To me, that means my I/O subsystem should be as fast and capable as possible. For example, looking at the block diagram [1] of Intel's P45/ICH10 chipset [2], it appears that the link between the north and south bridges is only 2 GB/s. I would think that any raid level that requires the CPU (e.g. parity calculations) would clog that link fairly quickly, at least if large block transfers are taking place. And then I wonder what impact that has on the performance of the NIC(s) (I don't know how much a NIC has to talk to the CPU). Then there are chips like nvidia's 8200 [3] that don't separate the north and south bridges. I can't find a block diagram on their website, but I found a few via google "nvidia 8200 block diagram". [4] It looks like the 8200 MCP is connected via HT3 (don't know exactly what that means/implies), but everything is connected to this one chip (PCI, SATA, PCI-Express, NIC, etc). Anyone have any suggestions on getting a motherboard with the most I/O bandwidth? [1] http://www.intel.com/products/chipsets/P45/pix/p45_blockdiagram.gif [2] http://www.intel.com/products/chipsets/P45/index.htm [3] http://www.nvidia.com/object/geforce_8200mgpu.html http://www.nvidia.com/object/mobo_gpu_tech_specs.html [4] http://www.hardwarezone.com.sg/img/data/articles/2008/2453/GeForce_8200_Block_Diagram.jpg http://www.pcper.com/images/reviews/507/GeForce_8200_Block_Diagram.jpg http://media.arstechnica.com/news.media/GeForce8200.jpg -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
