Is it necessary to eject a usb flash drive?

Question

From my understanding, the commands to safely eject a usb flash drive is now written into the generic drivers on all windows programs, so its safe to pull the drive out cold.

Also, how is it that the files could get corrupted? When I pull the drive out, I always close the files first, so theyre no longer in use. So doesnt this mean the files are not being read/written, and there is no risk of corruption?

However, in class, some people have criticized me for not 'stopping' the drive before pulling it out.

Simply put: who is right?

Answer 1

What typically happens is that to speed up access to the USB drive the computer will store what you write out to it in memory and then write it out in the background even after it has appeared to be finishing writing to the drive.

This makes using the USB drive seem quite a bit faster (since writes are almost instant) but means that if you pull it out before the computer has had a chance to actually finish the write then you will corrupt a file.

You can set a computer up not to do that if you want.

In general though you should do the proper thing and stop the drive first although it's quite safe to just remove it without stopping if you haven't written anything to the drive (and the 5 V power is supplied as long as it's plugged in). You won't damage anything just pulling it out though (the worst that'll happen is a file still being written gets corrupted and the computer along with people around you will complain).

Answer 2

Usb sockets, from the moment they are activated when you boot your computer, carry a constant 5 volt supply. For this reason, although not reccomended, if you plug a usb device in while the computer turned on, holding the connector loose at the front of the socket and slowly pushing it in, you will see small sparks on occasions if you look closely.

Whether or not it is particularly dangerous in terms of hardware damage to plug and unplug usb devices while the pc is on... well, I guess it depend on the device. Generally speaking, it's pretty safe, but I wouldn't like to guarentee that EVERY usb device is hot swappable.

Of course, I'm only speaking on theory from what I know and what I've seen, but personally, if I'd just spent £300 on some delicate piece of USB hardware, I'd try to avoid the power surge, however unlikely it was to damage it. If it's a gamepad or a mobile phone (cellphone) charger, I don't really care.

One thing I do know though, is that unplugging or replugging USB hardware while the computer is on running windows does sometimes crash the OS, producing a BSoD with a stop message mentioning (usually) USB related files. It doesn't seem to happen all that often though. I'm not 100% sure, but I believe it happens when a device is in use when you unplug it, and using the Safely Remove Hardware function ensures that the device is not in use so that it can be unplugged without crashing windows.

Hope this helps. Any little inaccuracies will be corrected I'm sure.

Answer 3

Its safe to eject USB drives before you remove them...