On 10/13/2015 05:25 PM, Greg Freemyer wrote:
On Tue, Oct 13, 2015 at 1:54 PM, Anton Aylward
wrote: On 10/13/2015 01:42 PM, Greg Freemyer wrote:
I think the real reason is simply money. They put better parts in SSD than in thumb drives. Even the USB3 Sandisk thumb drives I buy are "slow".
No, there is some "technology" behind it.
* SATA and eSATA are 'star wired' whereas SB are bus wired.
If you have any other USB device around it will slow down (aka convey slowest speed) all otehr USB devices.
* SATA and eSTAT are autonomous devices whereas USB are CPU controlled.
Disks have a long history of being 'smart' and often integrated with some kind of DMA so that many blocks can ba transfered all at once. With the move to 4K and 4K file systems this can be accelerated.
USB isn't actually a character by character device like a UART but it is more demanding of the CPU than a disk.
Anton,
I think you underestimate the improvements of USB-3 over USB-2.
There is also USB 3.1, but I don't have any of those devices yet.
From http://www.digitaltrends.com/computing/what-is-usb-3-1-when-will-it-be-relea... == The biggest improvement for the USB 3.1 standard is a boost in data transfer bandwidth of up to 10 gigabits per second. The new SuperSpeed USB specification in Generation 2 of USB 3.1 delivers improved data encoding and efficiency, doubling the speed of the Generation 1 standard (5Gbps). ==
Back to USB-3 and my real world experience:
I am a "heavy" USB-3 user. On my lab machine right now I have a 10-port USB-3 hub. Similar to http://amzn.com/B00GSLMTQ8
Connected to it are 2 (USB-3 <--> SATA) adapters.
These are the adapters: http://www.frys.com/product/7157332?site=sr:SEARCH:MAIN_RSLT_PG
In the adapters I have 2 1TB SSD drives.
http://www.frys.com/product/8144495?site=sr:SEARCH:MAIN_RSLT_PG
I also have 2 1.5TB USB-3 drives plugged into ithe hub. I semi-routinely copy 100GB of data from one of those drives to another. I also do large scale binary searches of the data.
Let me assure you that from a performance perspective USB-3 is close to SATA. What is not close is a 16GB Sandisk USB-3 Thumb drive, nor any other thumb drive I have used.
Thumb drives simply have slow electronics and it has nothing to do with the USB-3 interface.
Greg
Oh, and I just noticed: In USB3 mode, with proper USB3 cabling, you are transferring data over the two USB3 pairs, while in USB2 mode you are using the original 'singleton' cable for switching direction. Have I explained that properly? Greg, will all your USB3 stuff even work with USB2 cables? Heck, I know my tablet charges over twice as fast with the USB3 cable over the USB2. Perhaps ther's something more to it? -- A: Yes. > Q: Are you sure? >> A: Because it reverses the logical flow of conversation. >>> Q: Why is top posting frowned upon? -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org