在共享資料時，透過usb集線器連線的兩個驅動器能否繞過計算機？

如果您有多個硬碟驅動器連線到一個USB集線器，那麼複製的資料是先透過計算機移動，還是直接透過USB集線器本身移動？今天的超級使用者問答帖子回答了一位好奇的讀者的問題。...

如果您有多個硬碟驅動器連線到一個USB集線器，那麼複製的資料是先透過計算機移動，還是直接透過USB集線器本身移動？今天的超級使用者問答帖子回答了一位好奇的讀者的問題。

今天的問答環節是由SuperUser提供的，SuperUser是Stack Exchange的一個分支，是一個由社群驅動的問答網站分組。

圖片由itBox24（Flickr）提供。

問題

超級使用者讀者IAmJulianAcosta想知道兩個USB集線器連線的驅動器是否可以透過USB集線器直接傳輸資料並完全繞過計算機：

If I connect two USB drives to an external hub and I copy data from one drive to the other, does the data go through the computer or will the USB hub manage the data? Does this have some performance benefit?

當資料從一個USB驅動器複製到另一個USB驅動器時，將採用什麼路徑？

答案

超級使用者貢獻者lzam、Luu Vinh Phuc和fixer1234為我們提供了答案。首先，勒扎姆：

No, this will not work. All the data you are copying will need to be read by the computer from the source drive before it is copied to the target drive.

If anything, having two hard-drives connected to the same USB hub might slow things down. If you have multiple devices connected to the hub, they have to share the bandwidth.

接著是盧永福的回答：

USB is a host-driven protocol, not a peer-to-peer standard like firewire. Drives are just devices, they are not hosts that control or decide anything. Without the host, they cannot even interact with the outside world.

Assuming that you can connect the two drives like that, how will they know which files and/or folders you want to copy? How will they know which drive to copy from and will they overwrite duplicated files? How will they behave if the drives are full?

我們的最終答案來自fixer1234：

A USB hub is just a way to share a connection to the computer when you do not have enough USB ports for all the devices you want to connect. Devices connected to the computer through a USB hub never talk to each other. The USB hub ensures that traffic between the computer and the connected devices goes to and from the right device as if each was literally connected to a USB port on the computer.

There is no performance benefit and there may be a performance detriment. The USB hub itself is connected to the computer through a USB connection, so everything connected to the USB hub has to share the bandwidth of that connection. Hard-drives can c***ume a lot of the USB hub’s bandwidth and affect the performance of other devices attached to the USB hub. You generally do not want to connect hard-drives through a USB hub at all because of that.

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