THE BOOK--Playing The Percentages In Baseball

I will delete any post that accuses me of deception of any kind.

I know that early versions of USB drives required you to dismount them before physically removing them from the computer, but did not think that applied to those made in the last few years.

As long as no files are open or being transferred, I just yank it out and haven’t had a problem.

One time though I left it in the back of my work PC during the day shift while I was working nights. One of the day employees went to my PC to write large amounts of data onto a removable HD, wich they plugged in to another USB, but wiped and then attempted to write the files to my USB instead. They didn’t understand why it said “Insufficient Disk Space.” Everything I had was gone and of course not everything was backed up.

Brian: I always figured it was some sort of old wives tale.  I didn’t have anything opened, and even if I did, it should only affect the file that is open.  Why would the index to the files be affected (which is I presume what changed)?

It’s almost like it was going through some sort of defrag when I pulled it out.

I’m sure some of the bright minds can explain it to us.

I can remember the first one I bought had instructions on proper dismounting and removal.

Also, on NCIS, where Gibbs is generally portrayed as not being very computer literate, there was an early episode where he just grabs the flash drive out of the USB and the others just look at him with this shocked look on their faces as in “He didn’t just do that!”

I have never heard or read anything about the proper way to remove a flash drive, I had no clue it mattered. What am I missing?

My understanding has long been that users of the three major operating systems (Windows, Linux, and Mac) should always unmount/eject external drives. Yes, there may be some system-level precautions implemented by the OS vendor, but this Lifehacker piece from a couple days ago indicates unmounting is still a wise choice due to the threat of file or disk corruption.

http://lifehacker.com/5863810/do-i-really-need-to-eject-usb-drives-before-removing-them

There’s actually a Mac/Windows difference in terms of USB drives.

Macs use a pretty large buffer of some sort, and so you *really* have to eject it, otherwise you’re likely to brick the flash drive in the process of buffer write/read. The benefit is that it’s much faster.

With Windows, there’s no buffer, so you can generally yank at will. But of course there’s a small buffer involved in writing to anything so you can get unlucky if you yank your drive at the wrong time in the buffering process.

Tom - I believe you use windows, right? So, you really had bad luck on that. Me, I lost a drive on a Mac the first time I didn’t eject so that’s why I read up on this stuff.

This seems like a good excuse to ask, “Why aren’t you using the cloud for PC to PC file transfers?”

I wouldn’t care if it was an advertisement, but your overall attitude/hypersensitivity to criticism is amusing to me and others.

Macs use a pretty large buffer of some sort, and so you *really* have to eject it, otherwise you’re likely to brick the flash drive in the process of buffer write/read.

The use of “brick” should be used very carefully. It means a device is as dead as a doorstop and forever useless without replacing internal components. This is well beyond file/disk corruption, and they should not be confused with bricking.

The core issue is that operating systems cache changes to output devices. This means the system memory has the update, but it may not get written immediately on the device. At some point the cached changes are flushed to the storage device (i.e. physically written on the device).

Typically this happens when the system is otherwise less busy, so after a period of idleness or doing something else it should be OK simply to yank a drive. Most of the time.

The biggest risk is that if you happen to unplug the drive while the OS is in the process of writing to it, then the file system on the drive can be left in a corrupt state. Depending on the extent of the damage, recovery programs may or may not be able to retrieve your data.

So the bottom line is that it’s safest to unmount/eject a drive always. Often, if not almost always you can get away without doing so, but as Tango discovered, sometimes you can get burned.

A sudden loss of power to your computer can cause similar effects of leaving a file system in an incoherent state.

I have never done the proper eject, but I always wait a minute before removing the drive.

Occasionally my Vista-powered laptop will tell me my drives need to be scanned and fixed when I insert them, but doing this/not doing this doesn’t make any difference, as no files have ever been corrupted (until now, because I’m talking about it, so I’m sure the next time I do it I’ll destroy the drive).

JD - I’m not too familiar with Vista, but I can think of two possibilities that might trigger scanning of a drive:
1. The previous time the drive was removed, it wasn’t left in a fully clean state, so the OS is trying to recover from that. A file system is designed to be reasonably fault tolerant, so this probably will work most of the time.
2. Some systems (I know GNU/Linux ones usually do this) will automatically scan a drive for errors every N times you insert it. There’s a tradeoff between better safety by scanning more frequently and the time it takes to scan, which is proportional to the amount of data on the drive.

As to why systems cache writing to devices, it’s a tradeoff to improve usability. If every time you saved a file the computer had to wait until it was done before doing anything else, the computer would seem much more sluggish. Also as more programs auto-save without conscious action by the user, this problem would become worse (the OS simply knows a program is trying to write a file; it doesn’t know whether this was because the user did something to trigger it or not).

10/NaOH

The process does actually brick the USB drive. You can’t just reformat it—it becomes unusable absent some really involved rehabilitation process.
I can re-find all the webpages I found on the issue when it happened to me if you’re interested.

mettle/14: I’ve seen hundreds of drives incorrectly unplugged from Macs without ever hearing of one being bricked. No, I don’t think that means it’s okay to do that, but the worst I’ve seen is an occasional need (maybe 3 or 4 instances) to repair the drive using the built-in software Apple provides (Disk Utility). So, yeah, if you get a chance I’d be interested in seeing those articles.