Working with External Drives

Learn how to scan, clean up, and safely manage external drives and removable media

SquirrelDisk provides seamless support for external drives, USB flash drives, and other removable storage devices. This guide covers everything you need to know about working with external media.

Automatic Detection

SquirrelDisk continuously monitors your system for connected storage devices:

Real-Time Drive List

The disk list automatically updates:

• Refresh interval: Every 2 seconds
• Auto-detection: New drives appear without restarting the app
• Auto-removal: Disconnected drives disappear from the list
• Visual distinction: External drives display with a special removable drive icon

You don’t need to manually refresh the disk list. SquirrelDisk polls your system automatically and updates the interface when changes are detected.

Identifying External Drives

External drives are easy to spot:

• Icon: Removable drive icon (different from internal disk icon)
• Label: Drive name and mount point
• Capacity: Total space and available space
• Usage bar: Color-coded based on how full the drive is

Green: 0-60% full
Yellow: 60-70% full
Red: 70-100% full

Scanning Removable Drives

Scanning external drives works exactly like scanning internal disks:

Quick Scan (Default)

1. Connect your drive

   Plug in your external drive and wait for it to appear in the disk list.

2. Left-click to scan

   Click on the drive to start a quick scan (min-ratio: 0.001).

3. Wait for completion

   The scan progress displays while analyzing the drive.

Full Scan

1. Right-click the drive

   Right-click on the external drive in the disk list.

2. Full scan begins

   A comprehensive scan starts (min-ratio: 0) that analyzes every file.

External drives are typically smaller than internal disks, so even full scans usually complete quickly.

Performance Considerations

Scan Speed Factors

External drive scan performance depends on:

1. Connection type:

   • USB 3.0/3.1: Fast
   • USB 2.0: Moderate
   • USB 1.0: Slow

2. Drive type:

   • SSD: Very fast
   • HDD: Moderate
   • Flash drive: Variable

3. File system:

   • exFAT: Good performance
   • NTFS: Good on Windows, slower on macOS/Linux
   • FAT32: Moderate
   • HFS+/APFS: Good on macOS

Optimization Tips

1. Use quick scan first

   Start with a quick scan to get an overview, only use full scan if needed.

2. Close other programs

   Close applications that might be accessing the drive (backup software, antivirus, etc.).

3. Use USB 3.0 ports

   Connect to the fastest available USB port on your computer.

Scanning while other programs are actively reading/writing the drive can slow down the scan and may give inaccurate results.

Cleaning Up External Drives

External drives are ideal candidates for cleanup:

Common Cleanup Targets

1. Old backups: Outdated backup archives taking up space
2. Duplicate files: Multiple copies of photos, videos, or documents
3. Temporary files: Cache files, temp folders from various programs
4. Large media files: Old videos or high-resolution images you no longer need

Cleanup Workflow

1. Scan the drive

   Complete a scan of your external drive.

2. Navigate to large folders

   Use the sunburst chart to identify the largest folders.

3. Review contents

   Drill down into folders and review files in the sidebar.

4. Select items to delete

   Drag unwanted files and folders to the deletion area.

5. Verify selection

   Right-click items to verify their contents before deleting.

6. Execute deletion

   Click the Delete button to permanently remove items.

The real-time chart updates after deletion let you see exactly how much space you’ve freed on your external drive.

Safely Ejecting Drives

After cleaning up an external drive, you should safely eject it:

Before Ejecting

1. Complete all deletions

   Ensure any pending deletions have finished.

2. Return to disk list

   Navigate back to the main disk list screen.

3. Close any open file managers

   If you right-clicked items to view them, close those file manager windows.

Ejection Methods

SquirrelDisk doesn’t include a built-in eject function. Use your operating system’s eject mechanism:

Windows

1. Click the “Safely Remove Hardware” icon in the system tray
2. Select your drive from the list
3. Wait for the “Safe to Remove Hardware” message

macOS

1. Open Finder
2. Click the eject icon next to the drive name in the sidebar
3. Wait for the drive to disappear from the desktop

Linux

1. Open your file manager
2. Click the eject icon next to the drive
3. Or use command line: umount /path/to/drive

Always safely eject external drives before unplugging them. Removing a drive while SquirrelDisk (or any program) is scanning it can cause data corruption.

Common Use Cases

Cleaning a Full Backup Drive

1. Scan the external backup drive
2. Navigate to the backup folder
3. Identify old backup sets
4. Delete outdated backups to free space
5. Verify new backups can now be created

Organizing a Photo Drive

1. Scan your external photo storage
2. Find folders with the most images
3. Review and delete duplicates or blurry shots
4. Identify the largest video files
5. Remove videos you don’t need

Preparing a Drive for Reuse

1. Scan the drive to see what’s on it
2. Review the sunburst chart for an overview
3. Select all top-level folders for deletion
4. Execute deletion to clean the drive
5. Verify the drive is mostly empty

For complete drive wiping, use your operating system’s format utility after using SquirrelDisk to remove specific files.

Platform-Specific Behavior

Windows

• External drives appear with drive letters (E:, F:, etc.)
• Removable flash drives are automatically detected
• Network drives may appear if mounted

macOS

• External drives appear at /Volumes/DriveName
• Both USB drives and mounted disk images appear in the list
• The /Volumes path itself is excluded from root scans
• Time Machine drives are shown but may require admin permissions to scan

Linux

• External drives typically mount at /media/username/DriveName
• The /media path is excluded from root scans
• You can still scan individual drives by selecting them from the list
• Some drives may require root permissions to fully scan

Troubleshooting

Drive Not Appearing

If your external drive doesn’t appear in SquirrelDisk:

1. Check connection: Ensure the drive is properly connected
2. Verify mounting: Open your file manager to see if the OS recognizes it
3. Wait for detection: The auto-detection runs every 2 seconds; wait a moment
4. Check filtering: Some drives are filtered out (boot partitions, system volumes)
5. Try a different port: Some USB ports may not work correctly

Scan Taking Too Long

If scanning seems to hang:

1. Check the connection: USB 2.0 or older is significantly slower
2. Close other programs: Stop any other software accessing the drive
3. Try quick scan: Right-click was used for full scan; try left-click for quick scan
4. Check drive health: The drive may have hardware issues causing slow reads

Cannot Delete Files

If deletion fails on external drives:

1. Check permissions: Ensure the drive isn’t read-only
2. Verify file system: Some file systems require specific permissions
3. Close other programs: Files open in other programs cannot be deleted
4. Check write protection: Some USB drives have physical write-protect switches

macOS users may need to grant SquirrelDisk “Full Disk Access” in System Preferences > Security & Privacy > Privacy for external drive access.

Best Practices

Regular Maintenance

1. Scan external drives monthly
2. Delete accumulated temporary files
3. Review and remove outdated backups
4. Keep at least 10% free space on backup drives

Before Important Backups

1. Scan the backup drive
2. Clear old backups to make room
3. Verify sufficient free space
4. Safely eject and reconnect before backing up

When Sharing Drives

1. Scan before giving drives to others
2. Delete any personal or sensitive files
3. Review the sunburst chart to ensure nothing is missed
4. Check hidden files by scanning from the root

Keep your external drives organized by regularly scanning and cleaning them with SquirrelDisk. This prevents the “I don’t know what’s on this drive” problem and ensures you always have space when you need it.