I use a nearly full 10TB external hard drive to store video files. Over the past few days, it has occasionally disappeared from my PC until I unplugged and reconnected it. Interestingly, the computer still played the device-disconnected sound when I unplugged it even though the drive was no longer visible.
I ran CHKDSK, which reported "Corruption was found while examining the volume bitmap," and then appeared stuck at 100% for roughly ten hours. Task Manager still showed active reading at around 130–200 MB/s, so I wasn't sure whether the scan was simply taking a long time because the drive is nearly full or whether something was seriously wrong.
Event Viewer also showed an I/O operation being retried, a warning that Disk 6 had duplicate disk identifiers, and an error involving a paging operation on another hard-disk device. The drive being checked was Disk 6, so I'm unsure whether that last message is related. The drive is a Seagate One Touch Hub and is less than two years old, although it may already be outside its warranty period.
Should I have stopped CHKDSK, or was it reasonable to let it finish? Do these symptoms suggest failing hardware, and how can I check the drive's SMART health data?
3 Answers
Keep at least two local copies on separate storage devices, plus another copy somewhere away from the computer or home. Cloud synchronization services are not automatically backups, and a backup is only useful if the files can be restored. If buying several backup drives is currently too expensive, prioritize irreplaceable files first and avoid continuing to fill or stress a drive that is already disconnecting.
The first priority is to copy anything important off the drive to another physical device. Intermittent disconnections, retried I/O operations, and filesystem corruption can all be warning signs of a drive or USB enclosure beginning to fail. Even if CHKDSK finishes successfully, that only means it repaired or verified filesystem structures; it does not prove the hardware is healthy. Check the complete SMART attributes with a suitable disk-monitoring utility, and replace the drive if it reports bad, pending, or uncorrectable sectors. Do not treat this drive as the only copy of anything important.
The CHKDSK scan eventually finished, and it did not appear to remove many files. I still wasn't sure whether that meant the drive was safe to keep using.
The drive model and its SMART values are important. A utility that can read SMART data through the external enclosure should show whether the disk has reallocated sectors, pending sectors, or uncorrectable read errors. If the enclosure prevents SMART access, the drive may need to be connected through another compatible adapter. The duplicate disk-identifier warning can sometimes come from cloned disks or enclosure-related identification issues, but it does not explain away the disappearing drive and I/O retries.
Multiple backup drives are difficult to afford for a large collection, so I have also been comparing online backup providers. They are expensive too, but I understand that keeping only one copy is risky.