May 1, 2004
Back on March 14, while explaining USB Drives, Jeff Levy stated: "Hot Swappable is a good thing, means you can pull the drive. In some of the old machines you had to actually click on an icon and essentially get permission...you don't have to do that anymore."
Now, 48 days later, Levy warns us that we all need to "park" our USB devices before unplugging them. Stating that once USB devices are connected, "you should not under any circumstances remove them while Windows is running, until you park them because when you remove them you run a risk. Remember that USB cables, USB devices, are connected to a port that carries both data and electricity, and when you yank them you run the risk of having a static electricity attack that could destroy the motherboard, it could destroy the device. It is dangerous, it is unseamly, and it's not a good thing to do." Levy then (correctly) gave the steps to remove a device, ending with, "...when it says it's safe to disconnect that device, it is parked. And now there's no electricity flow to it."
Reply
Parking is an old term for the process whereby a hard drive's read/write heads are placed in an area of the disk that isn't used for data (the landing zone). Modern hard drives will Auto-Park when they lose power, whereas older drives did need to be Parked (using a utility) before the computer was turned off.
Next, the USB plug is a grounded connection. Therefore, as long as the device is connected, a build up of Static Electricity isn't a problem because the device is not insolated from the computer. Static electricity is only an issue when the device is first plugged in.
Considering that the Universal Serial Bus is designed to be Hot Swappable, and thus have devices plugged or removed while the Bus is powered, the possibilty of damage from plugging and unplugging is infinitesimal. Which brings us finally to why we shouldn't just unplug some USB devices.
USB devices which can store data do require several steps to remove them. The steps are as follow: Double-click the "Unplug or Eject Hardware" icon in the System Tray and from the new window select the device and click the Stop button.
Contrary to Levy's statement, Stopping a device does not turn off the power to its port. Part of the Stopping process involves removing the device's drive letter (if it has one), but most importantly flushing any unwritten data to the device. Without going through the Stopping process there could be data in RAM that would be lost because it wasn't written to the device.
Mp3 clips for both quotes are here: March 14th and May 1st.
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