Partitioning an external hard drive allows you to divide the disk into separate logical sections that function as separate drives. This can help organize your data and free up space. However, if not done carefully, partitioning can result in data loss. Follow these steps to safely partition your external drive without losing any files.
Why Partition an External Hard Drive?
There are several reasons you may want to partition your external hard drive:
- Organize data – Partitioning allows you to separate data types like documents, photos, music, etc. onto their own sections.
- Isolate sensitive data – A partition can keep sensitive files like financial records or work documents private from other users.
- Use multiple file systems – Each partition can have a different file system which provides compatibility with various devices and operating systems.
- Free up space – Dividing the drive into partitions allows you to free up space from one section without losing data from the other partitions.
- Install multiple operating systems – On bootable external drives, partitioning makes it possible to install and boot multiple operating systems without them interfering with each other.
- Limit partition size – Partitioning prevents any one section from using up all the space on your drive.
Risks of Partitioning an Occupied Drive
The main risk associated with partitioning an external drive that already has data stored on it is potential data loss. Here are some of the issues that can lead to that:
- Resizing partitions – If you shrink an existing partition to make room for a new partition, it could result in data loss if you inadvertently shrink it too small.
- Drive errors – Errors during the partitioning process could corrupt data or affect partition integrity.
- Accidental formatting – Formatting a partition will erase all its data. Accidental formatting of the wrong partition could occur during the process.
- Partition loss – If issues are encountered, it may be impossible to recover a lost or damaged partition.
- Unsupported file systems – Converting to an incompatible file system during partitioning can make data inaccessible.
To avoid these risks, it is essential to partition carefully and have a full backup before proceeding.
Back Up Your Drive Before Partitioning
To safely partition your occupied external hard drive, the very first step is to create a full backup of all the data on the drive. This provides you with a restore point in case anything goes wrong during partitioning. Here are some ways to back up your drive:
- Cloning software – Use disk cloning tools like Macrium Reflect or Clonezilla to make an exact copy of your entire external drive. This will replicate both used and unused space byte-for-byte.
- Imaging software – Imaging only copies used space. Use imaging tools like Macrium Reflect in sector-by-sector mode or Win32 Disk Imager to create an image backup file.
- File copy – Manually copy all files and folders from the external drive to another drive with enough free space. Copy hidden files and system files too.
- Cloud backup – Use an online backup service like Backblaze or Carbonite to securely backup your drive to the cloud.
The advantage of disk cloning and imaging is that it captures all data as well as the file system structure. File copy only gets your personal documents and data files. Choose a backup method suitable for your specific needs.
Disconnect the External Drive Before Partitioning
The external hard drive must not be connected to your computer during the actual partitioning process. This is to prevent any software from writing to the drive during partitioning which could lead to data corruption.
Once you have backed up its data, disconnect the external drive from your computer. If partitioning a bootable external drive with an OS installed, remember to shut down the system fully before disconnecting the drive.
Select a Partitioning Tool
There are a number of excellent partitioning tools available to safely divide your external hard disk without risking data loss:
| Partitioning Tool | Supported Platform |
|---|---|
| Windows Disk Management | Windows |
| Disk Utility | Mac |
| GParted | Linux |
| EaseUS Partition Master | Windows |
| AOMEI Partition Assistant | Windows |
| Paragon Partition Manager | Windows/Mac |
The Windows Disk Management console is a native Windows tool that gets the job done but has a dated interface. Third party tools like EaseUS Partition Master, AOMEI Partition Assistant and Paragon Partition Manager offer more flexibility and user-friendly graphical interfaces.
On Mac, Disk Utility is fully capable of partitioning external drives easily. For Linux, the best free tool is GParted which works across a wide range of disk types and file systems.
Guidelines When Using Partitioning Software
When using your selected partitioning tool, follow these guidelines:
- Only partition external drives – Avoid partitioning system disks or drives with OS installed.
- Unallocated space – Only partition unallocated space on the external drive.
- Non-destructive actions – Use only non-destructive partition actions like create, delete, format, resize.
- Quit all other software – Close all other apps before partitioning to avoid interference.
- Apply changes carefully – Review all changes made before applying them to avoid unintended results.
Create Partitions on the External Drive
The actual process of partitioning an external hard drive without losing data varies slightly across tools but follows the same general workflow:
- Connect the external drive to your computer.
- Open your selected partitioning software.
- Select the external disk from the list of available drives.
- Review existing partitions and layout.
- Unallocated space is where new partitions will be created.
- Decide number, size and file system of new partitions.
- Assign drive letter (for Windows) or mount point (for Linux/Mac).
- Add new partitions in the unallocated space without deleting or resizing existing partitions.
- Click Apply to save changes.
- Format new partitions if needed without formatting existing ones.
This creates the new partitions in the free space on your external drive without touching existing partitions and data stored on them.
Partition Alignment for Optimal Performance
For optimal speed, ensure partitions are aligned properly on sector boundaries. Advanced formatting like 4K sector drives require special care for alignment.
On Windows, choose dynamic disk type rather than basic when given the choice. This auto aligns partitions. On Mac and Linux, choose ‘Align to: MiB’ in the partition creation options.
Choosing Partition Sizes
Determine the right size for each partition based on estimated usage. Don’t make partitions too small that they fill up soon. Leave room for growth.
For portable external drives, a common setup is:
- 25-35% for Mac/Windows compatibility and data exchange
- 50% for Time Machine or File History backups
- 15-25% for general everyday storage
Select a File System
The file system defines how data is organized and stored on a partition. It also determines compatibility and supported features.
For external drives, common file system choices are:
- exFAT – Cross-platform compatible. No size limits.
- NTFS – Native Windows file system. Needed for bootable Windows partitions.
- HFS+ – Native Mac file system. Needed for bootable macOS partitions.
- EXT4 – Linux file system. Stable and full featured.
An exFAT partition can act as a common point for data exchange between Windows and Mac machines. Select file systems based on your specific partitioning needs.
Safely Disconnect the External Drive
Once partitioning is successfully completed, it is important to safely disconnect your external drive before physically removing it from your computer.
On Windows, use the Safely Remove Hardware icon in the system tray. On Mac, eject the disk using Finder. These steps ensure any cached writes are flushed to disk before disconnecting.
For portable external SSDs, avoid simply pulling out the drive without properly ejecting to prevent file system corruption.
Conclusion
Partitioning an external drive without loss of data requires careful planning and execution. Always have a full backup before beginning. Use the unallocated space on the drive to add new partitions without modifying existing ones. Select partition sizes wisely and choose appropriate file systems.
With a sound backup and reliable partitioning software, you can securely partition occupied external drives for better organization and optimal use of storage space.