What is a Bad Sector?
A bad sector is a section of a hard disk drive (HDD) or solid state drive (SSD) that has become physically damaged or unreadable by the drive controller (Wikipedia, 2022). When a bad sector occurs, the data stored in that section gets lost or corrupted.
Bad sectors most commonly occur due to physical damage to the disk surface, such as scratches or contamination. They can also be caused by manufacturing defects or deterioration over time. SSDs are less susceptible to physical damage than HDDs, but their NAND flash memory cells can wear out or fail with heavy use (How-To Geek, 2013).
The drive controller marks bad sectors so they are not used for data storage. However, if critical system files are within a bad sector, it can prevent the operating system from loading properly. Bad sectors will gradually accumulate over the lifetime of a drive until it completely fails.
Signs You Have a Bad Sector
There are a few common signs that may indicate your hard drive has bad sectors:
Computer freezing or crashing – Bad sectors can cause system instability and crashes, especially if the operating system tries to access data in those sectors. Your computer may freeze or randomly reboot if a bad sector is encountered.
File corruption – Trying to open files that are stored in a bad sector can lead to errors or corrupted data. You may get error messages when trying to access the file or the file may open incorrectly.
Errors when reading/writing data – When the hard drive attempts to read or write data in a bad sector, input/output errors may occur. You may see error messages referencing the disk, sector or unable to access storage device.
Other signs include strange noises from the hard drive, very slow drive performance, the operating system needing excessive time to boot, and difficulty defragmenting the disk. These issues typically point to physical damage on the drive platters where data is stored.
Back Up Your Data
Before attempting to repair bad sectors, it is critically important to back up your data. A failed repair could result in irreversible data loss, so having a current backup is essential. According to The New York Times, the most reliable backup option is to use an external hard drive. Popular models like the Western Digital My Passport Ultra provide ample storage space and USB 3.0 speeds for quickly backing up your data.
Other recommended backup methods include:
- Cloud storage services like Dropbox, Google Drive, or Microsoft OneDrive. These provide offsite backups accessible from any device.
- Online backup services like Backblaze which continuously back up files.
- Bootable backup tools that clone your entire hard drive like Macrium Reflect.
It’s best to use multiple backup methods for redundancy in case one fails. Always verify backups completed successfully before proceeding with bad sector repairs.
Check for Bad Sectors
There are a couple ways to check for bad sectors on your hard drive in Windows 10.
Using CHKDSK Scan in Command Prompt
One method is to use the CHKDSK (Check Disk) utility via the Command Prompt. Here are the steps:
- Open an elevated Command Prompt by typing “cmd” into the Windows search bar, right-clicking the result, and selecting “Run as administrator”.
- Type “chkdsk C: /f” (without quotes) and hit Enter. Replace C: with the letter of your hard drive you want to scan.
- CHKDSK will scan your drive and repair any bad sectors it finds.
For more information on using CHKDSK, see this Dell support article.
Checking SMART Data with Third Party Tools
You can also use free third party tools like CrystalDiskInfo to check the S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology) data from your hard drive. S.M.A.R.T. monitors drive attributes like reallocated sectors that indicate problems like bad sectors.
Fixing Bad Sectors
Windows includes built-in tools to help fix bad sectors on your hard drive. The most common tool is CHKDSK, which stands for Check Disk. To use CHKDSK to fix bad sectors:
1. Open the Command Prompt as an administrator.
2. Type “chkdsk C: /f /r” (without quotes) and hit Enter. Replace C: with the letter of your hard drive that needs checking.
3. CHKDSK will scan your drive and attempt to repair any bad sectors it finds [1]. This can take a while depending on the size of your hard drive.
You can also use the /x option with CHKDSK to have it dismount the drive before scanning, which can be more effective at finding and fixing errors. The command would be “chkdsk C: /f /r /x”
If CHKDSK is unable to repair the bad sectors, you may need third party software like HDD Regenerator. This tool scans your entire hard drive surface and attempts to repair damaged sectors by re-magnetizing the disk platters [2]. It can often fix sectors that built-in Windows tools cannot.
Replace Affected Files
Once you know which files have been affected by bad sectors, the next step is to replace them. This involves identifying the corrupted files from your backup and replacing them with undamaged versions.
Go through your backup and look for files that correspond to the damaged ones on your hard drive. You may be able to identify them easily based on filename and size. Some backup software also flags files that were corrupted or missing during the backup process.
Once you’ve identified the affected files in your backup, you can replace the damaged copies on your hard drive. Simply copy the good version from your backup over to the hard drive, overwriting the corrupted version. Make sure you replace the files in the same location they were originally in.
If you don’t have a backup available, you may need to redownload or recopy the affected files from their original source. For example, you could reinstall software or redownload photos, videos, music files, etc. This takes more time but still allows you to recover the important data.
Replacing damaged files from backup is usually quicker and easier than redownloading. That’s why it’s critical to maintain a complete backup that you can restore from in the event of bad sectors or other drive errors. Backup regularly to limit your data loss and recovery time.
Isolate Bad Sectors
If bad sectors cannot be repaired, it is recommended to isolate and lock them to prevent future use. This can be done using disk utility tools like Macrorit Disk Scanner. These tools will scan the drive and identify all bad sectors. You can then choose to lock these sectors to prevent the operating system from writing data to them again.
To isolate bad sectors:
- Download and install a HDD scan tool like Macrorit Disk Scanner.
- Open the tool and select your drive to scan.
- Once the scan completes, it will list all detected bad sectors.
- Choose the option to lock or isolate all listed bad sectors.
- The tool will then mark these sectors as damaged and prevent future writes.
Locking bad sectors prevents further data loss. While the sectors remain inaccessible, locking them allows the rest of the drive to operate normally. However, if too many sectors are locked, it may be wise to replace the damaged drive instead.
Deal with Persistent Bad Sectors
If the bad sectors continue to persist after trying the previous methods, more drastic measures may be required. One option is to repartition the hard drive to avoid the areas with bad sectors. This can be done by resizing and shifting partitions with disk management tools like Partition Wizard.
Another more involved option is to perform a low-level format of the drive using specialized tools like HDD Low Level Format Tool. This completely erases and recreates the hard drive’s partitioning and file system structure. However, a low-level format should only be done as a last resort, as it will result in complete data loss. Back up important files first.
Ultimately, if the bad sectors remain after trying all of these methods, the hard drive is likely damaged and should be replaced if possible.
When to Replace the Hard Drive
At some point, it becomes more cost effective to simply replace the hard drive rather than attempting repairs. There are a few signs that indicate the hard drive is failing and should be replaced:
If the bad sector count is rapidly increasing, this indicates the drive is deteriorating. According to users on Reddit, once bad sectors start appearing, it’s best to replace the drive as soon as possible.
Excessive bad sectors that cannot be repaired also indicate it’s time for a new hard drive. If chkdsk cannot repair the sectors, they are likely unrecoverable. As one Super User poster notes, more than 200 bad sectors often means replacement is needed.
Frequent freezing, crashing, or very slow performance can mean the drive is failing. If issues persist after attempting repairs, it likely means irreversible physical damage has occurred.
Strange noises like clicking or grinding coming from the hard drive are a sign mechanical components are wearing out and replacement should be considered.
Ultimately, if the drive is older or refurbished, replacement is preferred once bad sectors appear since they likely indicate the drive is reaching the end of its lifespan. At that point, it becomes risky to store important data on the drive.
Preventing Bad Sectors
There are a few things you can do to help prevent bad sectors from developing on your hard drive in Windows 10:
Use disk maintenance tools regularly. Run CHKDSK and Disk Defragmenter on a regular basis to monitor your drive health and optimize file storage. Scheduling weekly or monthly scans can help catch issues early.
Shut down your computer properly. Always use the Shut Down option in Windows instead of just powering off. This ensures the drive parks its heads and closes any open files to avoid corruption.
Avoid physical damage. Dropping or jarring your laptop or external drive while powered on can cause mechanical failure and bad sectors. Handle storage devices carefully.
Upgrade older drives. Hard disks deteriorate over time, especially after a few years of heavy use. Replacing aging drives can improve performance and reliability.
Maintain a stable power supply. Use a surge protector and avoid sudden power interruptions that could potentially damage the drive.