Slashdot Asks: Do You Need To Properly Eject a USB Drive Before Yanking it Out? (daringfireball.net)

In a story earlier this week, Popular Science magazine explored an age-old topic: Do people need to safely eject a USB stick before they pull it from their computer? The magazine's take on it -- which is, as soon any ongoing transfer of files is complete, it is safe to yank out the flash drive -- has unsurprisingly stirred a debate. Here's what the magazine wrote: But do you really need to eject a thumb drive the right way? Probably not. Just wait for it to finish copying your data, give it a few seconds, then yank. To be on the cautious side, be more conservative with external hard drives, especially the old ones that actually spin. That's not the official procedure, nor the most conservative approach. And in a worst-case scenario, you risk corrupting a file or -- even more unlikely -- the entire storage device. To justify its rationale, the magazine has cited a number of computer science professors. In the same story, however, a director of product marketing at SanDisk made a case for why people should probably safely eject the device. He said, "Failure to safely eject the drive may potentially damage the data due to processes happening in the system background that are unseen to the user."

John Gruber of DaringFireball (where we originally spotted the story), makes a case for why users should safely eject the device before pulling it out: This is terrible advice. It's akin to saying you probably don't need to wear a seat belt because it's unlikely anything bad will happen. Imagine a few dozen people saying they drive without a seat belt every day and nothing's ever gone wrong, so it must be OK. (The breakdown in this analogy is that with seat belts, you know instantly when you need to be wearing one. With USB drives, you might not discover for months or years that you've got a corrupt file that was only partially written to disk when you yanked the drive.)

I see a bunch of "just pull out the drive and not worry about it" Mac users on Twitter celebrating this article, and I don't get it. On the Mac you have to do something on screen when you eject a drive. Either you properly eject it before unplugging the drive -- one click in the Finder sidebar -- or you need to dismiss the alert you'll get about having removed a drive that wasn't properly ejected. Why not take the course of action that guarantees data integrity? What are your thoughts on this? Do you think the answer varies across different file systems and operating systems?

Comments

Re:Depends.

[Spazmania]

If your operating system was programmed well, the IO call writing to the USB drive would not return until all write buffers were flushed, would not permit large write buffers to a USB drive -and- nothing else would attempt to write the USB drive in the background.

Your operating system was not programmed well. Quick Removal only gets close.

You must unless you want to deal with lost data

[Artem S. Tashkinov]

Safe eject/removal is the only way to guarantee that file buffers are flushed and metadata is in a consistent state.

If you're OK with losing files, or having chunks of your free space marked as occupied, then don't use safe eject.

I usually do

[jason777]

I always eject it, but sometimes it says its in use and won't let me. But I want to pull it out NOW, so too bad its getting yanked out.
I also use a program called Hotswap! that ejects alot better than the windows one, AND lets me do sata drives and things that normally don't show up in the windows eject.

Re:What are my thoughts on this?

[TeknoHog]

The problem is that you do not know when the transfer is complete.

I'm also baffled about this level of idiocy in a /. article. I guess things that were obvious to us geeks 15-20 years ago are completely new to today's "digital natives".

That said, these things only became obvious to me when I moved to Linux back in the day. I learned about things such as mounting filesystems and a lot of other fundamental machinery that must be going on in Windows too, but it's hidden from the user. But there are these occasions when you absolutely need to unmount.

Back in the days of Windows 3.1, writing to floppies would halt everything else, and it would be clear when the transfer was complete. There was not much multitasking or write caching going on anyway, so it was OK. Today we take those for granted, but in turn it means we need to be explicit about ejecting devices.

The point about spinning hard drives is somewhat orthogonal, though. Simply unmounting the drive won't power it off. So you often need to yank the plug out while the drive is spinning. This can be hard to do safely with small drives and short cables.

Software fix

[gurps_npc]

The computer should simply have a symbol on the taskbar/similar area that says when it is safe to remove the drive or not.

Re:Depends.

[Joce640k]

I remember back in the 1980s when the Commodore Amiga used to say:

"You MUST put the floppy disk back in or data loss could occur".

(or something like that)

If only modern operating systems had such technology.

Re: yes,

[Anonymous Coward]

One thing I noticed about Ubuntu's file caching policy is that it writes everything except some amount which just hangs out in the file cache, and only when you try to safely unmount the disk will it try to write the rest of the cache regardless of how stale it is. Utterly ridiculous and just goes to show Linux devs don't know what they are doing.