[SOLVED] Transfer speed question

[wm3797]

When copying files from USB flash drive to desktop's SSD, why does the computer uses the USB flash drive's READ speed and NOT the SSD's read speed? This is confusing.

 

[USAFRet]

When copying files from USB flash drive to desktop's SSD, why does the computer uses the USB flash drive's READ speed and NOT the SSD's read speed? This is confusing.

In any data transfer, speed depends on the speed of the slowest device in the chain.

Writing from USB flash drive to an internal SSD< the flash drive can only serve the data so fast. The high speed SSD is left waiting a lot.

Think fire hose and garden hose.

No matter how big the fire hose is...if it is being fed by a garden hose, thats all you'll get at the other end.
And it works the other way. No matter how much you can pump out of a fire hose (SSD), the garden hose (flash drive) can only accept so much of it.


The transport mechanism has effects as well.
Writing from a system with a fast SSD, through ethernet, to another system with a fast SSD....the ethernet in the middle is the slow device.
Both SSD's are faster, but you can only pump so much through the ethernet cable.

 

[wm3797]

In any data transfer, speed depends on the speed of the slowest device in the chain.

Writing from USB flash drive to an internal SSD< the flash drive can only serve the data so fast. The high speed SSD is left waiting a lot.

Think fire hose and garden hose.

No matter how big the fire hose is...if it is being fed by a garden hose, thats all you'll get at the other end.
And it works the other way. No matter how much you can pump out of a fire hose (SSD), the garden hose (flash drive) can only accept so much of it.


The transport mechanism has effects as well.
Writing from a system with a fast SSD, through ethernet, to another system with a fast SSD....the ethernet in the middle is the slow device.
Both SSD's are faster, but you can only pump so much through the ethernet cable.

What I don't understand is, how come its using the USB flash drives read speed, the SSD is writing data onto itself, why is it NOT using its own read speed, lets say for arguments sake, the USB flash drives read speed is 10x faster than the SSDs. Isnt the SSD reading the data and then writing it onto itself?

 

[USAFRet]

What I don't understand is, how come its using the USB flash drives read speed, the SSD is writing data onto itself, why is it NOT using its own read speed, lets say for arguments sake, the USB flash drives read speed is 10x faster than the SSDs. Isnt the SSD reading the data and then writing it onto itself?

Because data can only be read from the flash drive, at whatever speed the flash drive serve up.
The write speed of the SSD is mostly sitting around waiting.

You are Reading from the flash drive, and Writing to the SSD.

 

[wm3797]

Because data can only be read from the flash drive, at whatever speed the flash drive serve up.
The write speed of the SSD is mostly sitting around waiting.

You are Reading from the flash drive, and Writing to the SSD.

So the computer uses the SOURCE's read speed, when writing data from the SOURCE to the DESTINATION?

 

[USAFRet]

So the computer uses the SOURCE's read speed, when writing data from the SOURCE to the DESTINATION?

Both source and target are important.

If reading from a fast SSD, writing to a slow flash drive...performance is similar to doing it in the other direction.
The slowest device in the chain dictates.

 

[wm3797]

Both source and target are important.

If reading from a fast SSD, writing to a slow flash drive...performance is similar to doing it in the other direction.
The slowest device in the chain dictates.

I understand the slowest device in the chain part, its reasonable. I just don't understand why it would use another drive's read speed and not its own. I mean, it has its own read speed, right?

 

[USAFRet]

I understand the slowest device in the chain part, its reasonable. I just don't understand why it would use another drive's read speed and not its own. I mean, it has its own read speed, right?

Its not "using" the speed of the other.
It's just that is what influences the overall speed.

 

[Nemesia]

I understand the slowest device in the chain part, its reasonable. I just don't understand why it would use another drive's read speed and not its own. I mean, it has its own read speed, right?

The SSD has it's own read speed yes but you're not reading the files from the SSD to move it to the SSD. You're reading the files from the USB flash drive using the USB flash drive read speed and moving it and using the SSD write speed.

Then you apply the weakest link limitation. SSD writing speed fire hose is limited from the weak USB flash drive reading speed garden hose.

 

[wm3797]

The SSD has it's own read speed yes but you're not reading the files from the SSD to move it to the SSD. You're reading the files from the USB flash drive using the USB flash drive read speed and moving it and using the SSD write speed.

Then you apply the weakest link limitation. SSD writing speed fire hose is limited from the weak USB flash drive reading speed garden hose.

Oh I see. It seems kind of weird how this whole read/write speed works

 

[Nemesia]

Oh I see. It seems kind of weird how this whole read/write speed works

It's not weird. It's the notion of you thinking that a drive can use it's own read speed to go read inside another drive that is confusing you.