On 7/3/2014 1:57 PM, Greg Freemyer wrote:
On Thu, Jul 3, 2014 at 12:51 AM, Dirk Gently <dirk.gently00@gmail.com> wrote:
Greg Freemyer wrote:
All,
I happened to run a USB3 throughput test recently and it wrote 5 TB in 7 hours. I used a USB3 hub to let me hook up 5 1 TB drives and wrote to them simultaneously.
That's about 200 MB / sec.
It's the first time I've ever apparently saturated USB3. Does anyone know if 200MB / sec is a good max USB3 throughput?
fyi: Per the spec, it should be possible to hit 500MB/sec., but real world seldom hits the spec limits so 200MB/sec may be as good as it gets. If not, I may need to look for a better USB3 hub. (I do a lot of high bandwidth transfers in my job.)
Max rate is basically how fast the serial lines can push/receive data between the wire and the host or device.
You might be able to sustain maximum speeds when using something like a static memory device, but probably not even for flash memory (in either a stick of SSD device) because flashing new data is comparatively slow.
And spinning platters with read/write heads on seeker arms have no chance of keeping up that kind of speed.
The above reply assumes the bottleneck is the disk drive. I agree that is likely the case when a single disk is in use via USB-3. My statement is that when I go from one disk (108 MB / sec) to 2 disks (120 MB/sec) I am not seeing a linear increase in bandwidth or even close to it.
Further, when I go to 5 disks, I seem to max out the USB-3 connection at 200MB/sec. That is disappointingly low to me, but it may be as good as it gets.
If I could get faster throughput by getting a better USB-3 hub, I'd like to know. As I'm working with a laptop Greg
But as explained previously, unless you are doing some magical "send once + receive on all 5" (which you said you were not doing), you are really only dealing with one disk at a time on either end of the wire. One receiving disk maxes out at 108 Two receiving disks: Second drive takes advantage of first being maxed (not read to receive) and it (#2) receives while #1 is busy. They take turns By the time you have 5 targets, you've probably maxed out your sending disk and the wire is waiting for data. -- _____________________________________ ---This space for rent--- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org