How to Fix Bad Sectors on an External Hard Drive in Windows 10/11

Bad sectors aren’t a good look on any hard drive. If some bad sectors have started to appear on your external hard drive, they may be revealing a problem that could get worse with time. But, what are they exactly? Are they something you can ignore, or are they an early warning sign of your external hard drive’s upcoming demise?

In this article, we’ll explain what they are and how you can fix bad sectors on an external hard drive.

What are Bad Sectors on a Hard Drive

Every hard drive contains spinning magnetic disks that store your data. Each disk is divided using sectors. Bad sectors are parts of a disk that are no longer usable due to it being permanently damaged. When a bad sector appears, there’s a good chance the data is lost, depending on the type of bad sector it is. Operating systems, like Windows, will automatically mark the sector as unavailable so no data is written to it going forward.

It’s normal for hard drives to have a few bad sectors, but once a disk starts to accrue a large number of bad sectors, it generally points towards disk failure.

Hard drive bad sectors come in two varieties: physical and logical.

• A physical bad sector is the result of physical damage, such as the hard drive head making contact with the disk or overheating issues.
• A logical bad sector can be caused by software, malware, and interrupted disk write processes.

Physical bad sectors cannot be repaired. Moreover, you cannot recover data from them. Instead, they’re marked as unusable, and the data residing in that sector is lost. However, logical bad sectors do have a chance of being repaired using repair tools. We’ll demonstrate how in the next section.

We talk about what usually causes bad sectors later in the guide, but for now, we need to focus on recovering your data before trying hard drive with bad sectors repair.

How to Recover Lost or Deleted Files From an External Hard Drive

Before you fix bad blocks on a hard drive using one of the solutions we’ve presented in this article, you should be aware that there’s a chance your data will be lost in the process. Therefore, before you proceed, we recommend recovering all data from the external hard drive first. To do so, you will need to use a data recovery tool.

We prefer Disk Drill for the job, as this is one use-case it excels at. And, since we’re dealing with an unstable drive, it has a built-in drive backup feature which we’ll be making use of for maximum data protection. It will require an additional drive of the same size or more, but will keep a copy of the recoverable data safe in the event the drive dies completely.

1. Download Disk Drill to your computer and open it.
2. Click Byte-to-byte Backup.
3. Select your external hard drive, then click Create backup.
4. Give the backup a name and specify where you want to store it. Click OK.
5. Go back to the Storage Devices section, and attach the disk image by clicking Attach disk image.
6. Select the disk image and click Search for lost data.
7. Click Universal Scan, which will search for all recoverable data. Advanced Camera Recovery is reserved for fragmented video recovery from cameras and drones.
8. Click Review found items.
9. Search the results and tick the files you want to recover. Your data will be grouped by Deleted or Lost, Existing, and Reconstructed, depending on its state. Click Recover when you’re ready.
10. Select a destination to save them. Don’t choose a location on the same external hard drive you’re recovering from. Click Next to finalize. The free version allows up to 100 MB of recovery, enough to recover essential files from bad sectors or just test out the software.

Backing up your drive isn’t the only data protection feature Disk Drill has. It also includes active S.M.A.R.T. monitoring, which we talk about further down.

How to Fix Bad Sectors on a Hard Drive

Fixing HDD bad sectors has no guarantee of success. But, there are some fixes you can attempt to implement in hopes of restoring it to working condition. Here are some solutions that will show you how to fix bad sectors on an external hard drive. Be sure to follow each step carefully if you’re attempting external HDD bad sector repair to avoid worsening the damage.

Method 1: Repair Bad Sectors Using Error-checking Tool

Windows includes a disk error-checking tool that utilizes the functionality of CHKDSK. This is by far the easiest fix on the list, as it doesn’t require you to install anything or tinker in a command-line interface (CLI). It will scan your drive for bad sectors and attempt to repair them. However, CHKDSK can cause data loss, along with other methods we’ve included. Therefore, we remind you to either recover the data now, or back up the drive for later recovery.

Follow these steps to scan your external hard drive for bad sectors using the disk error-checking tool:

1. Open File Explorer.
2. Right-click on your external hard drive, then click Properties.
3. Click Tools.
4. Click Check.
5. Click Scan and repair drive.

Method 2: Repair with CHKDSK

CHKDSK (CheckDisk) is the Windows repair tool that can repair bad sectors on external hard drives, and the one utilized by the error-checking tool in the last method. Therefore, it’s exactly the same in function, in terms of being able to scan your drive for logical and physical errors. Even so, we’ve included the CLI instructions for those who want more flexibility or just prefer a terminal interface.

The instructions below will guide you through how to repair bad sectors in an external hard disk using CHKDSK:

1. Right-click Start and select Terminal (Admin).
2. Type chkdsk D: /r. Replace D: with the drive letter used by your connected external hard drive. Press Enter.

Method 3: Repair with Repair-Volume

CHKDSK is a very useful command, but sometimes it misses the mark. The repair-volume command was released with Windows 8 and Server 2012. It is similar to CheckDisk, with the benefit of added functionality. It can find and repair volume-related problems, such as bad sectors. Here’s how you can use the repair-volume command to repair a hard drive with bad sectors:

1. Right-click Start and select Terminal PowerShell (Admin).
2. Type Repair-Volume -DriveLetter D -OfflineScanAndFix. Replace D with your own drive letter. This will take the drive offline momentarily to try and fix it. Press Enter.

Method 4: Remap Bad Sectors

Using the third-party HDD bad sector repair tool, you can scan your external hard drive for bad sectors. If the program finds some, you can use the remap option to replace damaged or broken sectors with spare working ones. Technical users can minimize scan times by specifying the Logical Block Addressing (LBA) start and end blocks. We prefer to use Victoria, but this can also be done with tools like HD Tune or HDDScan to fix bad sectors/blocks on an external hard drive.

1. Download and extract Victoria.
2. Click Test & Repair.
3. Select Remap, and then click Scan.

Solution #5: Use Manufacturer Service Utilities

When dealing with an external hard drive or solid-state drive from a well-known brand like Seagate, Western Digital, or Toshiba, it’s worth checking if the manufacturer offers its own diagnostic utility.

Some popular options include:

• Seagate SeaTools
• Western Digital Data Lifeguard / Kitfox
• Samsung Magician (for SSDs)
• Toshiba Storage Diagnostic Tool

Since they’re built specifically for the brand’s firmware, they tend to deliver more accurate diagnostics, like surface scans, and in some cases, remapping or zero-filling bad sectors. We’ll be demonstrating what Samsung Magician looks like, and how to use its built-in tools. Keep in mind these instructions will be different for each brand of drive, so only use this as an example:

1. Download and install Samsung Magician.
2. Click Diagnostic Scan.
3. Click Start.
4. Samsung Magician will alert you to any errors it finds during the scan.

A short scan will be performed by default, but this can be changed to a full scan, or a SMART self-test for more coverage. Keep in mind, however, that these other scans will take longer.

Method 6: Perform a Full Format to Mark Bad Sectors

One of the most reliable ways to fix hard drive-related problems is by performing a format. In most cases, you can get away with a quick format to fix external hard drive errors. But, when it comes to the case of bad sectors, you need to perform a full format instead. A full format will scan every part of the drive for bad sectors. Bad sectors are then remapped to backup sectors so the problematic sector is no longer used.

While full formats are more effective, they take much longer and eliminate any trace of recoverable data. If you are planning to do a full format, make sure all the data is safe first.

Follow these steps to perform a format:

1. Right-click Start and select Disk Management.
2. Right-click your external hard drive’s partition, then select Format.
3. Specify the name and file system you want to use. Make sure Perform a quick format is unticked. Click OK.
4. Click OK when asked if you want to continue.

What Causes Bad Sectors on a Hard Drive

There are many reasons why each type of bad sector can manifest, and sometimes there’s really nothing you can do to prevent them. Here are some examples of what can cause physical bad sectors:

• Drive overheating – Your hardware has a specific temperature range that it can operate at. If your drive overheats and exceeds its operable temperature range, it can cause metallic components to expand and contract, damaging the read/write heads or magnetic platters.
• Faulty drive head – If the drive head gets misaligned and ends up making physical contact with the platters, it will most certainly lead to some level of data loss as a result.
• Power surges – Following a power outage, your computer may fall victim to a power surge, causing some delicate electronic components to become fried or damaged.

And here are some common causes behind logical bad sectors:

• Error Correction Code (ECC) mismatch – ECC is used to detect and fix data corruption. If there is a mismatch, it means the ECC mechanism has failed to fix it, and so the sector is marked as a bad sector.
• File system corruption – A file system can become corrupted due to improper shutdowns, resulting in a logical bad sector appearing.
• Incomplete write operations – When a write operation is interrupted, the information written to the drive will be incomplete. The data will become corrupted and lead to issues with file integrity, which could contribute to logical bad sectors.

When You Should Stop and Replace the Drive

While some bad sectors occur naturally over time due to regular use, a rapidly growing number of bad sectors is cause for long-term concern. The solutions outlined in this article will help you get the drive into working order, but it doesn’t guarantee stability. Physical problems worsen over time, and repaired drives shouldn’t be trusted to hold important data.

If you want to keep using the drive, it’s important to monitor the drive’s health. This can be done with software like CrystalDiskInfo, or even Disk Drill, the tool we mentioned earlier. Both display the key S.M.A.R.T. attributes Reallocated Sector Count, Pending Sector Count, and Uncorrectable Sectors. Suddenly rising values (for example, pending sectors increasing from 1 to 12 in a week) mean the drive is on its way out and should be replaced.

If using Disk Drill, S.M.A.R.T. monitoring can be enabled for each drive in the Extra Tools section. From then on, the health indicator will show 🟢 Green (healthy), 🟡 Yellow (warning), or 🔴 Red (critical).

Conclusion

The sudden appearance of bad sectors can be cause for concern, especially if they keep increasing at an alarming rate. Physical bad sectors cannot be fixed, but logical bad sectors do have a chance of being repaired.

Before implementing any fixes, start by recovering your data using a data recovery tool. Then, you try repairing the bad sectors using the built-in error-checking function. If that doesn’t work, you can also try running the repair-volume command in PowerShell. Victoria, a third-party tool, is also useful for remapping bad sectors. However, if all else fails, your last option is to perform a full format of the external hard drive.

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