Proper Ejection of External Drives Remains Necessary, Engadget Reports

According to the report, the old advice remains relevant because the operating system does not always stop working with a drive when the transfer bar completes. On macOS, for example, Time Machine and Spotlight can still engage an external drive after a transfer ends. Ejecting the drive tells the computer to finish whatever process is underway before the cable is pulled, reducing the risk of data corruption and incomplete file transfers.

Many unplugged drives appear to suffer no immediate consequences, but the action carries risk on Windows, Mac and Linux. If a transfer is still running in the foreground or background, removing the drive leaves the process incomplete and files potentially corrupted. Corruption can also be silent, so a user might delete an original file after believing it was copied, only to discover later that the version on a flash drive is damaged.

Removing a drive without ejecting can also corrupt the file system, which is the drive's record of what is stored where. An unannounced removal can leave half-updated information about files, one reason Windows asks users to scan and fix a drive when it is plugged back in. The Mac warning 'Disk Not Ejected Properly' is a warning rather than a sign of data loss, but the real problem occurs if a drive disappears mid-write, such as during a backup.

In rare cases, failing to eject an external drive can damage the partition table, which operating systems use like a table of contents to navigate the drive. Partition table damage can cause a computer to see the drive as unallocated or not initialized, making it unusable until it is repaired.

The report said it can sometimes be safe to unplug a drive without ejecting, mainly when the drive is idle. Idle means no applications are using it, no files are open and no transfer is happening. The caveat is that idle to a user is not always idle to the computer, which can start background processes without warning. Confirming whether a drive is truly idle can take longer than simply ejecting or unmounting it.

Safety also depends on the operating system. During Windows 10's lifetime, Microsoft made the Quick removal policy the default for removable drives, reducing the risk of an unsafe ejection at the cost of performance. Users can change this setting for any drive by right-clicking the Start button and choosing Disk Management, then right-clicking the removable drive in the bottom list, choosing Properties, clicking the Policies tab and selecting Quick removal or Better performance. On Mac, background processes such as Time Machine backups and Spotlight indexing make proper ejection important. Linux is the riskiest of the three because it relies heavily on write caching, so a transfer can look finished while still needing a few seconds to complete, and pulling the cable can leave data in memory instead of written to the drive.

Some newer drives include built-in protection against sudden disconnection to help prevent data loss or corruption. Those features can fail, so they should not be trusted blindly. The safest approach remains to eject or unmount an external drive before removing it. The process takes only a moment, and the operating system will warn if it needs to finish an operation.