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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?
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?
ask it in a Mac-Forum, with the question, how to disable the requester that pops up... much more fun...
I can't count the number of times I've tried to eject a USB drive, and Mac OS tells me it's "unable to eject the drive because it's in use."
Usually it's because Preview.app held onto some file descriptor for its stupid thumbnail of recent documents - not the list in the file menu, the one that pops up when you right-click on Preview in the Dock.
Apple used to promote the idea that the user is in charge. When I click "eject," the damn thing should eject!
It's akin to saying you probably don't need to wear a seat belt
No, no and no.
As you may know, risk = damage x chance.
When i don't wear a seat belt and get in a crash, i might die or suffer severe injuries. That's big damage.
When i loose a file, i lost a few bits. I usually couldn't care less. It might be a photo or mp3 file. It might be a failed backup. Worst case it's a fortune worth of bitcoin. But i won't die from it.
Don't make analogies that just aren't true. Don't pretend a lost bit is the same as a broken body part. And to be on-topic - i usually just `yank` my thumb drive out whenever i want. When i feel it's really important i might once in a blue moon go the official way. I'm perfectly capable of calculating the risk that i take. Saving many seconds on repeated actions weigh up against that one time i was to quick and spend a minute re-copying a file.
It's just the next episode of FUD - same as the 'experts' done with passwords. Just so now they have an excuse to blame the user if a flash storage fails (which they do): 'you probably yanked it out'.
A glitch a day keeps the bugs away.
If you haven't written anything to the USB, yes, it's completely safe. Any filesystem that's writing data just because of your passive reading of the disk is a) stupid, b) should have recovery for such, c) shouldn't be writing anything important (e.g. a last access time, maybe?)
If you have written anything to the disk, and it's synced to disk (i.e. activity light is idle) then, yes, it's safe. This may be dependent on OS and whether you can see any activity light. Modern OS should mount without write-caching for external drives unless told otherwise, and any half-decent filesystem should survive a forcible unmount in such circumstances
If the USB is still busy churning after you copied files to it, and you yank it? Yes, you're gonna lose data.
That a bunch of "nerds" can't figure this out after all the years we've had USB disks etc. (I remember starting with them in 95 OSR2 / Linux 2.0 personally?) really worries me.
Same as floppies before it. Floppy only being read-from? You can yank it. Floppy was written to but has now gone idle? You can yank it. Floppy was written to and it still pulsing / flashing? Leave it alone.
What is "ÃoesyncÃ"? [1]
A sign that Slashdot's text handling is pathetic.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
What are your thoughts on this? Do you think the answer varies across different file systems and operating systems?
You're kidding, right?
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
And what mount options. And what filesystem. And how busy the OS is and it's settings.
There are so many exceptions its best to just say always eject first. If you don't you are needlessly putting your data at risk.
Plenty of things could still go wrong. There is simply no guarantee that the OS will not be writing to the FAT due to some background process. Pull the drive at the wrong time and you corrupt the FAT. If one uses a journaling file system, yanking the drive becomes more feasible - but is still not a good idea.
Because all it does is change the choice to "Do I eject the drive properly, or do I check to make sure "quick removal" is enabled and then yank the drive?" Unless you already know it's been set (i.e. you personally set it previously for this drive for this instance), the latter takes more time than ejecting.
The #1 cause I've seen for corruption of data/partition information on USB flash and external HDDs is yanking it out too quickly, just before the copy has finished. In theory a journaling filesystem like NTFS should be immune to damage from this. But for some reason it occasionally seems to corrupt the partition table making the entire contents of the drive inaccessible unless you're skilled enough to repair it manually (usual cause seems to be the partition type number got changed).
That's a 10 minute or so repair process if you know what you're doing. If you don't, it's probably 30-60 minutes downloading the tools and stumbling around trying to figure it out. And if you obeyed Windows when it popped up the "You need to format this disk before you can use it" message when you plugged the drive in again, and formatted it, now you're looking at several hours for file recovery with no guarantee you'll be able to recover everything. (They really need to add a second line to that message saying that formatting will destroy any existing data.)
All this risk and time wasted just to save a few seconds by not ejecting. So I advise people to always eject the drive before yanking it. The seatbelt analogy is very appropriate. It takes very little time to do, but the rare consequences if you don't do it can be devastating.
The solid state USB drives essentially have their own mini OS that controls things. You have to give that a chance to get to a reliable state.
The OS should set those flags whenever the write operation has completed, not wait until a "clean shutdown" happens. There are lots of things that can happen between the file write and the time the partition gets unmounted (eg power or controller failure), not accounting for technical issues is a flaw.
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The problem is, it could change back to unsafe as you're pulling it. Computers operate at speeds way to fast for this. You'd have to do something like have a green light, yellow light, red light system where writes wait until a yellow light has been shown for a couple of seconds before they start. That would destroy performance.
Half the time I try to eject a USB drive in Windows it just says no and gives no reason...I yank it. It works fine next time. No problem. Windows is retarded, don't listen to it.
Horse shit.
I don't give a rat's ass what the drive is doing when you remove it. If you want to plug it into a Pentax camera without having to reformat it first, you'll eject or unmount the drive before removal.
Lots of other devices have this same problem. The drive records if it was properly ejected or not. You have to know for sure if you want the ability to use it with any compatible device on the next insert, or if you want to have to risk needing to re-insert it, and then eject, so that your device will trust you that the drive is in a known-good state.
It is not enough to know what the drive is doing "at the time," you have to know what the drive will be doing in the future too.