Data recovery software provides a way for users to attempt to recover lost or deleted files from their computers, external hard drives, USB flash drives, SD cards, and other storage media. When a file is deleted, it is not immediately overwritten by the operating system. Instead, the space it previously occupied is marked as available for new data. As long as that space has not been overwritten, data recovery software can scan the storage device and look for files that have been marked for deletion.
How does data recovery software work?
Data recovery software works by scanning the entire storage device sector by sector, looking for files types it recognizes. When it finds a file, it checks the file system’s index and looks for an entry for that file. If there is no entry, it means the file has been deleted. But because the contents of the file are still intact on the disk (until overwritten by new data), the data recovery software can rebuild the file and restore it.
Different data recovery software uses different techniques, but most follow a basic process:
- Scan the storage device to build a directory tree showing all existing files (including hidden and deleted files)
- Analyze the file system metadata, like the master file table in NTFS, to identify deleted files that are still recoverable
- Allow the user to browse through the tree and select files to try to recover
- Extract copies of those selected files and restore them to a safe location, such as a separate external hard drive
Advanced data recovery software is even capable of reconstructing lost or damaged partitions and recovering files from formatted or corrupted drives.
One technique used by data recovery software called file carving goes through the raw data on a drive looking for common file header and footer patterns. When it finds a starting and ending pattern that match a specific file type, such as JPG or PDF, it extracts the block of data between them as a recovered file. File carving can recover files when the file system metadata is corrupted or missing.
What kinds of files can be recovered?
Most data recovery software can recover all common file types, such as:
- Documents: .doc, .docx, .pdf, .txt, etc.
- Spreadsheets: .xls, .xlsx, .csv, etc.
- Presentations: .ppt, .pptx
- Images: .jpg, .gif, .png, .tiff, .bmp, etc.
- Video and audio files: .mov, .mp4, .mp3, .wav, .wma, etc.
- Emails: .pst, .ost, .eml, etc.
- Archives: .zip, .rar
Some data recovery software boasts the ability to recover more than 1,000 different file types. The specific file types supported will vary by program.
Database and specialized file recovery
Certain data recovery programs go beyond basic media recovery and also support formatted, corrupted, or deleted databases, email databases, and other specialized file types such as:
- MS SQL (.mdf, .ldf)
- MS Exchange (.edb)
- MySQL (.ibd)
- Access (.mdb)
- Outlook PST (.pst)
- QuickBooks (.qbw)
These require advanced knowledge of the database file structures and formats. Average users are better off using a dedicated database or email recovery service for those file types.
What factors affect the recoverability of deleted files?
When attempting to recover deleted files with data recovery software, success depends on several key factors:
As mentioned above, the chief factor is whether or not the space occupied by a deleted file has been overwritten with new data. The sooner data recovery is attempted, the less chance there is of overwriting.
If there are physical errors on the drive, caused by aging, mechanical failure, or damage, data recovery becomes much more difficult. The reliability of the disk’s surface and sectors is critical.
Complex proprietary data structures like databases, virtual machine files, and email stores have lower recoverability than common file types like Office documents or JPEGs.
The file system running on the storage device also affects recoverability. For example, recoverability rates tend to be higher for FAT-formatted drives than NTFS.
Cause of deletion
If files were deleted via the Recycle Bin or Trash, they stand a better chance of recovery than if they were permanently deleted using Shift+Delete.
Storage device type
Recoverability rates vary across device types. Generally, hard disk drives offer better recoverability than solid-state drives. Removable flash media often has lower recoverability than internal drives.
What tools are used by data recovery software?
Data recovery software utilizes different technologies and advanced techniques to extract deleted files. Here are some of the key tools used:
File system readers
In order to reconstruct the folder structure of a drive and identify deleted files, the software must be able to read the specific file system format, such as NTFS for Windows or HFS+ for macOS. This enables accessing the system metadata.
Data recovery software uses complex mathematical algorithms to match file patterns and reconstruct corrupted directory structures. This enables identifying files when metadata is missing or unclear.
To safely analyze drives and avoid further data loss, data recovery software often creates disk images or clones as working copies for scanning and file extraction.
As explained above, file carving looks at the raw binary contents of a drive and uses header/footer signatures to extract files without relying on filesystem metadata.
Storage media access
Some recovery software can access disk sectors at a very low level, enabling recovery from highly corrupted media. Specialized access to memory chips can recover data from USB drives and camera cards.
Tools like electron microscopes can scan drive platters at the bit level to extract data that is unreadable conventionally due to surface issues.
What are the capabilities and limitations?
Understanding the capabilities and limitations of data recovery software is important for setting proper expectations. Some key points:
- Works best soon after accidental deletion before space is overwritten
- Higher success rates for media failure than logical errors
- Better performance on conventional HDDs vs SSDs or flash media
- Supports recovery of most common file types
- Special methods required for complex databases, email stores, etc.
- No guarantee – depends on type and extent of data loss
- Requires technicians for mechanical or advanced logical recovery
- May take hours to days to scan drives and rebuild files
- Cost increases with complexity and urgency of recovery
While data recovery software can work miracles, it’s not magic – the laws of physics and disk technology still apply. Proper handling and backup practices remain imperative to avoid needing advanced recovery.
Can data recovery software recover files after reformatting or repartitioning a hard drive?
Yes, data recovery software often can recover deleted files even after reformatting or repartitioning a hard drive. This is because reformatting a drive does not actually erase the data – it only erases the filesystem information telling the operating system where files are stored. The actual file contents remain on the drive.
That said, there are a few caveats:
- The longer the drive remains in use after reformatting, the greater the risk of permanent data loss due to overwriting old contents with new data.
- Creating new partitions shrinks the available space for recovering old data, as that space may get overwritten with fresh data.
- Recovering after reformatting often requires advanced scanning algorithms to reconstruct folders and files when filesystem metadata is wiped clean.
- If full disk encryption was enabled, not even data recovery software can recover the files, since they remain encrypted.
So for the best chance of recovering files after a reformat or repartition, use the data recovery software as soon as possible before major changes to the drive contents overwrite the old data.
What are the chances of recovering overwritten files?
If a file has been completely overwritten by new data, even data recovery software cannot bring it back. The old contents have been fully replaced on disk by the new data.
However, keep in mind:
- It takes time to fully overwrite an entire drive with new data, so recently deleted files may still be recoverable.
- Some traces of overwritten data can remain due to the physics of hard drives and data persistence after deletion.
- Advanced techniques like magnetic force microscopy can sometimes recover remnants of overwritten data.
But these remnants represent only a tiny fraction of the original contents. So effectively, the chances of recovering an overwritten file are near zero using conventional data recovery software.
The best way to preserve important deleted files is to recover them before they have a chance to be overwritten.
Can data recovery software crack passwords and recover encrypted files?
Data recovery software alone cannot crack passwords or recover encrypted files without the proper encryption key. If the encryption is strong, the files remain securely locked without the key.
That said, there are a couple potential options for encrypted files:
- The password or key may be recovered through non-technical means, like finding it written down.
- A backup may exist from before the files were encrypted.
- Dictionary attacks or brute force cracking could guess a weak password.
- The password may be bypassable due to a flaw in the specific encryption software.
- A vulnerability in the operating system could theoretically allow decryption without the password.
So while directly decrypting strongly encrypted files is likely impossible, alternative routes may exist in certain circumstances. But data recovery software alone cannot just break the crypto and recover encrypted files deleted from disk.
Can data recovery software recover files after a disk crash or hardware failure?
Yes, data recovery software plays a crucial role in recovering files after a major hardware failure, like a head crash on a hard drive or failed controller on a solid-state drive. Software enables logical recovery when the drive is still partially accessible, and assists physical recovery when drive hardware itself needs repair.
If the drive hardware is damaged but intact, data recovery software can still scan and extract data from it as long as the components needed to read the disk remain functional. But with physical damage, recovery will require a clean room and specialists to repair or swap damaged components so the drive can communicate normally.
So in summary:
- Logical recovery of failed drives may be possible using software alone if hardware still kind of works.
- With physical damage, mechanical repair comes first, then software recovers the files.
- Specialized tools can assist technicians in repairing and recovering damaged media.
- But with total mechanical failure, a clean room is mandatory for any recovery hope.
Data recovery software and disk repair go hand-in-hand after hardware disasters – software alone cannot fix physically failed drives.
What are the best practices for using data recovery software effectively?
Follow these best practices when using data recovery software to ensure the best chances of successfully recovering deleted files:
- Don’t install data recovery software on the affected storage device – use a separate media.
- Backup data before attempting recovery to avoid further data loss.
- Act quickly before deleted files are overwritten.
- Scan and recover to a different drive than the data was lost from.
- Save recovered files to a safe location before attempting to open/access them.
- Use file-carving and read-only tools if the filesystem is corrupted.
- Leave difficult mechanical or logical recoveries to data recovery experts.
- Organize critical recovered files after completion.
Careful usage of data recovery software gives you the best chance of getting those important deleted files back intact.
Data recovery software provides a useful means to attempt recovering lost or deleted files, as long as the original space has not been overwritten. Usage and effectiveness depends on several factors, including how the files were deleted, storage device type, time elapsed, and techniques used. While data recovery software can seem like magic, it cannot overcome fundamental physics. Serious mechanical failures require disk repair first. Still, when used properly soon after data loss, it enables recovering otherwise inaccessible files.
|Data Recovery Software
|Supported File Systems
|NTFS, FAT32, HFS+
|Undelete Protection, Deep Scanning
|NTFS, FAT, exFAT
|Overwrite on Write, Virtual Hard Disk
|Advanced RAID Reconstruction