In Windows 7, before unplugging an external hard disk or flash drive, you are ideally supposed to use the Safely Remove Hardware option to make sure there aren't any writes still pending.

Suppose it has been several minutes since the last write nominally completed. Is it safe to assume that this is long enough for everything to be written to the disk, so that you can just go ahead and unplug the device?


No, but it does not mean it is a death sentence if you do.

You can not guarantee that all the writes have been flushed out, but after several minutes of sitting it is likely that the data is flushed out. However, you may have some issues with some filesystem maintenance things that don't happen until you unmount if you are in "Performance mode" (see the next paragraph)

However there is another option (and it is likely already set for 99% of all removable media). If right click on the device and go to properties. Then from there go to the hardware tab and find your device.
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Click Properties, then click on the Change Settings button on the new page. Go to the Policies tab.
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If you device is set to "Quick Removal" you can remove your device without going though "Safely Remove Hardware" without worrying about data loss.

If you do not have a Policies tab you likely skipped the Change Settings step.

  • Well, I usually just take out my flash drive when I know it's not in use, but I will be sure to use this setting. Thanks! – cutrightjm Apr 10 '12 at 2:52
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    Most complete answer! Images say more than a thousand words – kokbira Apr 10 '12 at 16:44
  • @ScottChamberlain Is plugging out a USB drive / hard drive without first "safely removing hardware" harmful to the physical disk? I'm not worried about data per se, but the lifetime of my physical USB drive / hard drive. Will it make the disk spoil faster / incur risks to events that may make the disk spoil faster? – Pacerier Jul 5 '12 at 16:13
  • @Pacerier For solid state drives the only ware should be just the normal ware from reading and writing the drive. If you are using a spinning disk the only concern I would have is if you plugged it in then immediately unplugged it that could maybe do something to the servo motor. However neither of these two things are related to the "safely remove hardware". One thing that could "damage" the drive is if you are set to "performance" mode you could cause errors in the file allocation tables, but if you are set to "quick removal" you will be fine. – Scott Chamberlain Jul 5 '12 at 16:31
  • @ScottChamberlain Hmm, but imagine I'm reading data (for example transfering data to another disk), and halfway I simply plug out the hard disk. Wouldn't this have a chance of damaging the physical disk in any way? – Pacerier Jul 5 '12 at 16:51

It depends what style you set the drive to (optimize for performance or quick removal). Some filesystem updates are not written in performance mode until the drive is manually unmounted (i.e. clicking Safely Remove Hardware). So long as your device is not in performance mode (i.e. in quick removal mode, so write caching is disabled), you can just remove the device.

If it is, you have no choice but to click Safely Remove Hardware. This is the only way (aside from manually doing it through Computer Management) to unmount the filesystem safely. If you don't, nothing will probably happen - but it certainly could, and the filesystem certainly won't be as reliable as a clean mounted/unmounted one.


There could be any number of background programs that you don't know about that cause read/writes.

For example, lets say that you open a file in an editor... you are using the editor and click the file menu... for all you know, it could be that your item is in the recent files list and just by invoking the menu, you are causing some action on the file.

...So, whilst it is safer, it is not as safe as just using Safely Remove Hardware!

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