External Hard Drive: 100 GB Used That is Not

This pointed to the issue. I have CCC snapshots consuming 110 GB.

### Check for APFS Snapshots (If Using APFS)

1. **List APFS Snapshots**: If your external drive is formatted with APFS, there could be snapshots consuming space.

sudo tmutil listlocalsnapshots /Volumes/YourExternalDrive

2. **Delete Snapshots**: Delete snapshots using:

sudo tmutil deletelocalsnapshots [date]

I didn't delete the snapshots as I might need them. I now know that the 100 GBs are used by CCC.

CCC stores its snapshots on the same volume as the source data, leveraging the APFS (Apple File System) feature for creating snapshots. These snapshots are located within the APFS container, and you can view and manage them using Disk Utility or through CCC’s own interface.

To check the snapshots, you can:

1. Open CCC.

2. Go to the “Tasks” sidebar.

3. Select the task associated with the volume.

4. Click on the “Snapshots” button.

Alternatively, in Terminal, you can use the tmutil command to view snapshots:

tmutil listlocalsnapshots /

This command lists all local snapshots for the specified volume.

These steps too didn't help:

Given that the above steps didn't resolve your issue, it might be useful to look into other potential causes and solutions. Here are some additional approaches:

### Check for Snapshots

1. **Local Time Machine Snapshots**: Sometimes, Time Machine creates local snapshots that can consume significant space. You can list and delete these snapshots using Terminal.

tmutil listlocalsnapshots /

To delete a snapshot, use:

sudo tmutil deletelocalsnapshots [date]

Replace `[date]` with the specific snapshot date.

### Check for System Integrity Protection (SIP) Related Files

1. **Boot into Recovery Mode**: Restart your Mac and hold down Command (⌘) + R until you see the Apple logo.

2. **Open Terminal**: From the Utilities menu, select Terminal.

3. **Disable SIP Temporarily**: Enter the following command:

csrutil disable

4. **Reboot and Check**: Restart your Mac and check if you can find and remove the hidden files causing the space discrepancy.

5. **Re-enable SIP**: Once done, reboot into Recovery Mode again and re-enable SIP with:

csrutil enable

### Check Disk Usage with `ncdu`

1. **Install ncdu**: `ncdu` is a disk usage analyzer that might reveal hidden space usage. You can install it using Homebrew:

brew install ncdu

2. **Run ncdu**: Navigate to your external drive and run `ncdu`:

cd /Volumes/YourExternalDrive

ncdu

This will provide a detailed breakdown of disk usage.

### Check for Corrupt Files or File System Issues

1. **Disk Warrior**: Consider using Disk Warrior, a third-party utility that can repair directory structures and might resolve space issues caused by file system corruption.

### Check for Sparse Bundle or Sparse Image Files

1. **Find Sparse Bundles**: Sparse bundle disk images can sometimes be created inadvertently. Use Terminal to find them:

find /Volumes/YourExternalDrive -name "*.sparsebundle"

2. **Inspect and Remove**: If found, inspect these bundles and remove them if they are not needed.

### Check for APFS Snapshots (If Using APFS)

1. **List APFS Snapshots**: If your external drive is formatted with APFS, there could be snapshots consuming space.

sudo tmutil listlocalsnapshots /Volumes/YourExternalDrive

2. **Delete Snapshots**: Delete snapshots using:

sudo tmutil deletelocalsnapshots [date]

### Reformat the Drive

As a last resort, if the issue persists and you can't identify the cause, consider reformatting the drive. Ensure you have backed up all necessary data before doing so:

1. **Open Disk Utility**.

2. **Select Your External Drive**.

3. **Erase**: Choose a suitable format (e.g., ExFAT, HFS+ for macOS, or APFS).

This process will remove all data on the drive, so make sure you have a complete backup.

If none of these methods resolve the issue, it might be worth consulting with a professional data recovery service or an Apple Support technician for a more in-depth analysis.

All the Below didn't solve help me find the 100 GBs:

It sounds like there might be hidden or system files consuming the extra space on your external hard drive. Here are some steps you can take to identify and possibly resolve the issue without having to back up and restore the entire drive:

### Check for Hidden Files and Folders

1. **Show Hidden Files**: Use the Finder method (Command + Shift + Period) to see if there are any hidden files taking up space.

2. **Use Disk Inventory Tools**: Tools like Disk Inventory X, DaisyDisk, or GrandPerspective can help visualize disk usage and identify large hidden files or folders.

### Check for System Files and Logs

1. **Temporary and Cache Files**: Sometimes, temporary files or cache files might take up significant space. Use tools like CleanMyMac or OnyX to clean up your system.

2. **System Logs**: Check if there are any large system logs or diagnostic reports. These are usually located in `/private/var/log` or `/Library/Logs`.

### Use Terminal to Find Large Files

1. Open Terminal and use the `du` command to find large files and directories. For example:

sudo du -sh /* 2>/dev/null

This command will list the size of directories in the root level. You can replace `/` with the path to your external drive.

2. Drill down into large directories to find specific files consuming space:

sudo du -sh /path/to/directory/* 2>/dev/null

### Check for Disk Errors

1. **Disk Utility**: Open Disk Utility, select your external hard drive, and use the "First Aid" feature to check and repair disk errors.

2. **fsck Command**: For a more thorough check, you can use the `fsck` command in Terminal. Unmount the external drive and run:

sudo fsck_hfs -fy /dev/diskX

Replace `/dev/diskX` with the correct identifier for your external drive, which you can find using `diskutil list`.

### Clear Trash and Other Storage

1. **Empty Trash**: Make sure the Trash is emptied, as deleted files on external drives may still reside there.

2. **Time Machine Backups**: If you use your external drive for Time Machine backups, they can take up significant space. Manage or exclude certain backups if needed.

By following these steps, you should be able to identify and resolve the issue causing the size discrepancy without having to go through the entire backup and restore process again.