Hi, On 07/28/2014 10:31 PM, Laszlo T. wrote: >>>>> I have some problems with Jmicron JMS567 (Sata 6 Gb/s -> USB3.0) >>>> mobile rack. >>>>> >>>>> I tried on different kernels: >>>>> 3.15.5 >>>>> 3.16.rc6 >>>>> >>>>> I got the following errors when I ran a mkfs.ext4 command and then >>>> the >>>>> device disappeared. >>>>> >>>>> Jul 26 19:54:37 debian kernel: [ 118.060026] usb 8-3: new >>>> high-speed >>>>> USB device number 2 using ehci-pci >>>> >>>> Hans, shouldn't we default to usb-storage rather than uas if the >>>> device >>>> supports both and isn't connected at SuperSpeed? >>> >>> We would give up command tagging needlessly. >> >> Right, that is what I was about to say. For testing purposes >> I've a Fedora rawhide install a ssd in a usb3 uas 2.5" enclosure, >> and it is much faster with uas in usb2 ports too. >> >> It looks like the device disconnects as soon as we start using >> multiple requests at once (it seems to disconnect immediately >> after the basic probing). >> >> This could be a power issue. Laszlo, what sort of drive is in the >> mobile rack, and how is it powered ? >> > > I don't think it is a power issue. > I'm using on desktop PC on usb2 port with just a simple cable but the > disk (WD5000LPVX) only consumes 1.4 Watts (read/write) and it is > stable on Windows.
http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-771437.pdf Says it uses 1.4 Watts "average", it has a rated peak power consumption of 1A, and a USB2 port can deliver only 0.5 A, so its rate maximum is twice as much as the USB2 port's maximum. Disconnection issues like you are seeing are typical for drawing too much power from the port. Using uas as the dmesg shows you are will allow us to send more commands to the disk at once (which is a good thing, it is faster) and as such will increase power consumption. Does the enclosure you are using have the option to provide external power, and have you tested things that way ? Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
