Am 24.10.2011 22:02, schrieb Grant Edwards: > On 2011-10-24, walt <w41...@gmail.com> wrote: > >> I just bought an add-on USB3 adapter and outboard USB3/sata docking >> station, and I've been comparing the performance with my old e-sata >> outboard docking station. Not so good :( >> >> After getting some unreliable results with hdparm, I settled on >> copying one 3GB file from one partition of the outboard drive to >> another partition of the same drive. These results are highly >> reproducible, and favor e-sata over USB3 by a large margin. >> >> Over at least six trials on each docking station I consistently get >> 105 seconds for USB and 84 seconds for e-sata, a 5:4 ratio in favor >> of e-sata. > > Not surprising. Did you expect that adding a gateway device to the > communication path and another protocol layer on top of SATA would > make things faster? > >> I used the same hard disk and the same pci-e slot in the same >> minimally-loaded machine for all the runs, and got very consistent >> results every time. >> >> Basically, the USB3/sata docking station gets the same throughput as >> the older sata 1 drives connected to the onboard pci sata controller, >> which is still pretty respectable for an outboard drive, I think. > > Yep, SATA performs the same as SATA. AFAIK, eSATA and SATA are > identical apart from the physical specs for the connector, a few minor > voltage level differences (to imporove noise tolerance), and hot-plug > support. >
Normal SATA also offers hotplug. Usually works, too. >> So, has anyone out there done similar tests on USB3 drives yet? > > There are disk drives that talk USB3 natively and aren't just using > USB<->SATA gateways? > Well, there is USB Attached SCSI (CONFIG_USB_UAS in the kernel). It supports command queuing and works for USB-2.0 and 3.0 (but has additional software overhead for USB-2.0). I've not yet seen a compatible device, though. Regards, Florian Philipp
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