At the suggestion of her computer helper, Mom is using a pair of USB flash drives to back up her new computer. It’s a good, simple strategy that should keep her data safe in the event that her new computer unexpectedly blows up. She did come up with a question though about using these drives:

I have my Flash Drive plugged in. Where do I locate its presence so that I can safely extract it? I find if I do leave it plugged in, the next time I want to turn my computer on, I get a message indicating an error and am not allowed to log on.

The short and simple answer: To remove the flash drive, double click on the “Safely Remove Hardware” icon in the system tray (the icon circled in red in the image at right). From the next window, select “USB Mass Storage Device” and click the Stop button. Click OK in the confirmation window and you’ll get a message that it’s ok to unplug the device. It will automatically re-enable itself when you plug it back in.

You can also just unplug it while the computer is turned off, to prevent it from complaining when you restart. The reason it does that is that the computer tries to find it’s start-up (boot) files on removable devices before looking on the hard drive. When it finds the device but not the files, it throws an error. Seems silly to me; it should ask you if you want to boot from the hard drive instead. But there you are.

The longer, more complete answer: Devices like flash memory drives connect through an interface called USB (Universal Serial Bus). The first USB standard was introduced way back in 1995 and was intended to reduce the number of connectors (also called ports) needed on a typical PC and simplify the configuration of external hardware devices. It has succeeded so well at this that many new computers today use only USB connectors for everything except audio and video.

A Typical USB Hub

A modern desktop computer will have four to eight USB connectors built in. Some will be on the back panel and some on the front. External USB Hubs may be also be connected, further adding to the available connections. A maximum of 127 connections may be used by a single computer.

When a USB device is connected, it is automatically discovered by the USB host. If that device is supported, it is automatically configured and made available for use. Flash memory drives are almost always supported natively (i.e., support was built in to the computer’s operating system) but many other devices need to have special software called a driver installed before the device will be recognized. This is what happens when you pop in the installation CD that comes with new hardware. In most cases, the driver must be installed before you connect the device for the first time.

Driver installation is a one time process, although you will need to install one for each additional device (camera, printer, MP3 player, etc.) that you need to connect. Once this is done though, plug the device in and it will automagically start working.

If USB is so smart, I hear you asking, why do you have to go through this special process to unplug things? Well, don’t tell anyone you heard it from me, but a lot of the time, you don’t. You can just pull the plug and the sky will not fall. There’s a pretty good reason not to do this though, especially with devices that have data written to them, like flash drives and external hard drives. Here’s why: for greater efficiency, data is often held temporarily in RAM (non-permanent memory) and only written to permanent storage periodically. If you unplug your permanent storage before it’s received all of its data, bad things tend to happen. Going through the “Safely Remove Hardware” procedure ensures that all of your data has been moved onto the removable device and your great American novel remains intact (if unfinished).

Any other questions about USB or removable devices? Please leave a comment.

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