On 10/5/2012 1:36 AM, Roman Mamedov wrote: > I would not recommend a PMP, with it your 5 disks will be limited to one SATA > port's bandwidth, which will not give you good performance. Roman is simply wrong here. The PMP will give far better performance in the OP's case than a 4 port PCI 32/33 HBA. With 4 disks the SiI 3826 PMP will provide 2.27x-4.5x better throughput per drive than a 4 port PCI 32/33 card. FYI: PCI bus, 32 bit, 33MHz 132MB/s total bandwidth SATAII singe channel 600MB/s duplex, 300MB/s unidirectional 4 port PCI 32/33 card 33MB/s per drive maximum PMP using 4 drive ports 150MB/s per drive maximum 75MB/s per drive unidirectional You failed to take the system bus connection of the SATA chip into account. A single SATAII channel is 2.27x faster than the PCI bus. Southbridge integrated SATA controllers typically have upstream bandwidth of 2GB-8GB/s depending on the chipset. Motherboard mounted discrete secondary SATA controllers that provide 2-4 additional internal or eSATA ports connect upstream via a PCIe x1 1.0/2.0 interface, good for 250 or 500MB/s unidirectional, 500MB/s or 1GB/s duplex, ~2-8 times faster than PCI 32/33. This is why nobody uses PCI HBAs, unless they have no other option. A single 3TB rust drive can stream at ~150MB/s, slightly faster than the PCI bus can accept the data. Recent SSDs can push 500MB/s, 4x faster than the PCI bus. This is precisely why I recommended the PMP solution over a 4 port PCI 32/33 HBA. -- Stan -- 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
