Max usb data transfer rate?
So I decided to get a 16 gb Kingston class 10 card for the phone, and wanted to see how fast it really was. I decided to write about 10 gb of movies and music to the card.
Using two built in card readers in two different laptops only gives me ~3mb/s. Using my brothers Sandisk Extreme III usb card reader I was able to achieve 11 mb/s. All these test were also using the supplied SD card adapter and the windows file transfer details
When I put the card in the phone and use the phone's cable I was stuck at a write speed of ~4.5 mb/s. Copying files back to my computer from the card in the phone gave me a read speed of ~10 mb/s
Do I have a buggy class 10 kingston card or is this a limitation of the data rate when copying to the card while it is still in the phone? Read/write speed from the Sandisk card reader was 20mb/11mb so I think the card is working as advertised.
I'm running windows 7 and the stock N1 rom. USB driver was installed from the android SDK package in preparation of rooting the phone.
04-21-2010 06:03 PM
This card seems to be working fine. The class is the minimum write speed, read speeds might be different. Different readers will perform differently. If you get consistent speeds on a particular device and consistent speeds using a separate device, then it sounds like an issue with the reader not the card
Originally Posted by nocturn
Since you see the right speed on some devices I would say it's fine.
You have that backwards.... reads are always faster than writes. Writes require both erasing and storing, whereas reads only require retrieval.
Originally Posted by number 9
This link might help: Secure Digital - Wikipedia, the free encyclopedia
This one's good too: [ame="http://en.wikipedia.org/wiki/Flash_memory"]Flash memory - Wikipedia, the free encyclopedia[/ame]
Those speeds sound pretty normal. USB 2 is 480Mbps (which is 60MBps). But there is some overhead, etc. so you're never going to get that rate.
Even when I transfer files between my SATA drives, I hardly ever get over 70MBps.
Also note that in many laptops the card reader is still connected to a USB hub internally.
I noticed that after posting.
Originally Posted by Beer Goggles