I'm not a geek or anything, and I'm slightly confused (and frustrated) by my hard drive performance at times. I have 4 SATA2 Western Digital drives, 7.2k boot and 5.4k storage. As a normal, not-too-techy person I know that SATA2 is rated for 3Gbps. Can someone explain then, why I'm seeing average transfer rates of 20~30Mbps? Same thing with flash drives. USB2.0 is rated for 480Mbps, but why am I seeing less than 5Mbps on most occasions? Nicholas
The sata speed is the maximum rate that data from a hard drive's buffer can be transferred across the interface. This is really a non issue for hard drives because no conventional hard drives can saturate even the sata 1 bus. Very little data is likely to be found in the hard drive buffer. The rpm of the hard drive determines part of the access time. Faster rpm reduces the time a drive waits until the requested data comes under the read/write heads. Contrary to popular opinion, faster rpm does not usually result in a faster data transfer rate. Faster data rates come more from denser platters, and accessing the longer outer cylinters of the drive. Bottom line is that there is not a heck of a lot of difference in performance among the whole range of hard drives. The real difference comes with a solid state drive(SSD). There is no mechanical motion, so access time is negligible. Data transfer times are equal, and usually much better. It is for SSD's that you might need the 6gb data transfer rate of sata 3. It would be unusual to get more than 2 ssd's, hence only 2 6gb sata ports are typiical. For hard drives and dvd's 3gb is twice the capability that you need. USB3.0 is new, and much faster. I imagine it is also a bit more expensive. For now, you will not usually see someone using more than 2 high speed external device. The chipset provides some things. In the case of P67, for example, you get (if I remember correctly)2 6gb sata, 4 3gb sata, and 14 usb2.0. Motherboard vendors may add more sata ports, usb3.0 ports and other attachments that they think is needed in the marketplace. I strongly support SSD's for the os and apps. They truly make a difference. Larger SSD's will usually be faster. Put it on a 6gb port, and specify sata mode = AHCI(not ide or raid) to get trim support. If you need more, gat a hard drive for overflow and storage. For backup, get a external drive with a usb3.0 interface. I think it is easier than e-sata which should also work. Cheers,
