When a file is deleted from a computer, it isn’t actually erased right away. The reference to the file’s data on the hard drive is removed from the file system index, making it seem like the file is gone. However, the data itself remains on the hard drive until it is overwritten by new data. This allows deleted files to be recovered using data recovery software as long as the original data hasn’t been overwritten.
But what about when a file is permanently deleted? Is it possible to recover a file after it has been permanently deleted? The answer is maybe, depending on the steps taken to permanently delete the file. Let’s look at how file deletion works and the factors that determine whether a permanently deleted file can be recovered.
How File Deletion Works
When you delete a file on your computer, either by hitting delete, dragging it to the recycle bin, or using Shift+Delete for a permanent delete, it is simply removed from the file system index. The data remains in place on the hard drive in the now “unallocated” space until it is overwritten.
Here is a simple explanation of what happens:
Normal File Deletion
1. You delete a file
2. The reference to the file’s data is removed from the file system index
3. The data remains in its place on the hard drive
4. The space the file occupies is now marked as “unallocated” and available to be overwritten
5. The file can be recovered using recovery software until the original data is overwritten by new data
Permanent File Deletion
1. You permanently delete a file (Shift+Delete on Windows)
2. The reference to the file’s data is removed from the file system index
3. The data remains in place on the hard drive
4. The space is marked as unallocated
5. The file can be recovered until the original data is overwritten
So whether a file is deleted normally or permanently deleted using Shift+Delete, the result is essentially the same – the data remains on the drive until overwritten. The key is avoiding or preventing the overwrite by new data.
Factors That Determine File Recoverability
When a file is permanently deleted, there are several factors that come into play in determining whether it can be recovered:
1. Time since deletion
The sooner data recovery is attempted after deletion, the higher the chances of file recovery. As time goes on, the deleted data has a higher chance of being partially or completely overwritten by new data. Attempting recovery immediately after permanent deletion provides the best odds.
2. Disk usage
How heavily the hard disk is used and how full it is plays a role. A heavily used disk with little free space has a higher chance of overwritten deleted data compared to a lightly used disk with lots of free space. The more the system writes new data to the disk, the greater the odds of deleted file data being overwritten.
3. Disk format
The format of the hard disk influences recoverability. Common formats like NTFS, FAT32, and exFAT overwrite deleted file space as part of normal operation. Other file systems like HFS+ on Mac don’t automatically overwrite deleted files. File recovery is generally easier on file systems that don’t natively overwrite deleted data.
4. Secure delete methods
Some operating systems and programs offer secure deletion methods that intentionally overwrite deleted file data to prevent recovery. For example, CCleaner’s Drive Wiper option writes over deleted file space with random data multiple times. If these methods are used on a file, recovery becomes nearly impossible.
5. Disk encryption
If the hard disk uses full disk encryption technologies like BitLocker on Windows or FileVault on Mac, it scrambles all the data on the drive, including deleted files. Encryption prevents recovery of deleted files since they can’t be decrypted even if found.
6. Physical disk damage
Physical damage to the hard disk like a head crash can make portions of deleted files unreadable, preventing recovery. Damaged disks often result in partial recovery at best.
Recovering Permanently Deleted Files
If you need to recover a file that has been permanently deleted from the hard drive and none of the above factors prevent recovery, it can often be achieved using file recovery software:
– Recovery software scans the drive and looks for file signatures of commonly used file types like JPG images, Word documents, Excel Spreadsheets, PDFs, etc.
– It can recover these deleted files by reconstructing them from the still intact data on the disk.
– Some advanced recovery programs may allow you to reconstruct an entire deleted file system.
Popular data recovery software capable of recovering permanently deleted files includes:
– Recuva – Free Windows recovery tool from Piriform
– EaseUS Data Recovery Wizard – Cross-platform with free and paid tiers
– Stellar Data Recovery – Paid recovery software for Windows, Mac, and Linux
– Disk Drill – Mac & Windows recovery app with free and premium options
– R-Studio – Advanced paid recovery software for Windows, Mac, and Linux
Scan Types
Most recovery applications will offer different scan types optimized for certain recovery scenarios:
– Quick scan – Fast scan that recovers recently deleted files
– Deep scan – Thorough scan ideal for permanently deleted files or formatted drives
– Forensic recovery – Advanced scan attempted to reconstruct entire file systems
Performing a deep scan maximizes the chances of finding files deleted long ago when using recovery software. Quick scans may be unsuccessful for permanently deleted older files.
Recovery Tips
Follow these tips when attempting to recover permanently deleted files:
– Don’t install the recovery software on the same drive as the deleted files. Use another disk or external drive.
– Save the recovered files to another drive, not the original.
– Avoid any further disk writes by shutting the system down after deletion and booting from external media.
– Use a deep scan optimized for finding lost data on the target drive.
Preventing Deleted File Overwrite
To maximize recoverability of deleted files, you need to prevent the permanent deletion from overwriting the data in the first place. Methods of accomplishing this include:
Unplug the disk
If possible, power down the machine and disconnect the hard drive after file deletion and before using recovery software. This physically prevents any overwrite of deleted data.
Boot from external media
Booting the system from an external hard drive or bootable USB drive keeps the disk with deleted files offline, protecting it from further writes.
Write blockers
Hardware write blockers allow read-only access to drives, blocking any writes to disk that could overwrite deleted file data.
Raw disk access
File recovery tools often have a mode that gives them direct access to disk sectors. This bypasses the operating system and prevents any further writes to the disk.
Recovery apps
Specialized recovery oriented operating systems and boot discs can be used that are designed to prevent overwritten deletion. For example, Kali Linux and Bootable Recovery Tools.
Secure Deletion Concerns
While recovering deleted files can be convenient, it can also be a security and privacy risk if sensitive files fall into the wrong hands. However, securely wiping deleted files also has some downsides:
Intentional Recovery Prevention
Secure delete methods intentionally prevent you from recovering your own files. If you securely erase an important file accidentally, recovery becomes impossible.
Disk Wear
The extra disk writes performed by secure deletion software can wear out drives more quickly. This shortens the usable lifespan of SSDs which have limited write endurance.
Performance Impact
The background wiping of deleted file space can negatively impact system performance until completed. This can temporarily slow down a system after deleting large files.
Difficult to Implement
Platforms like Windows and macOS don’t natively support secure file wiping. Third party tools are required which can be complex to properly configure and use.
For most users, basic deletion is sufficient. But those with highly sensitive data may want to utilize secure deletion methods despite the downsides. Properly implemented, it can greatly increase the difficulty of recovering permanently deleted files.
Recoverability In Summary
While deleted files can often be recovered from a hard drive, here are some key points to summarize recoverability of permanently deleted data:
– Deleted files are recoverable from hard disks until their data areas are overwritten by new data
– The likelihood of recovery depends on elapsed time, disk usage, format, encryption, and physical conditions
– Recovery software can find and restore recently deleted files if overwrite has not occurred
– Prevention of overwrite is key to allow recovery – disconnect disk, use write blockers, etc.
– Secure delete methods overwrite data specifically to prevent recovery
– For normal deletion, recovery is often possible if acted quickly before an overwrite occurs
So in summary, accidentally deleting a file permanently doesn’t necessarily mean it’s gone forever. The key is acting swiftly to restore the deleted data before it has a chance to be overwritten by the operating system or other disk activity.
Conclusion
While permanently deleting a file removes its reference in the file system, the actual data remains on the hard drive in many cases if it is not overwritten. With the right recovery tools and techniques, recovering previously deleted files is possible if the original data still exists intact. However, the likelihood of recovery diminishes over time as the deleted data areas get overwritten by new data. Acting quickly after permanent deletion provides the highest chances to restore deleted files successfully from the hard drive. Carefully considering data recovery scenarios can mean the difference between recovering important files and having them be unrecoverable if permanently deleted.