Data recovery is the process of salvaging data from damaged, failed, corrupted, or inaccessible secondary storage media when it cannot be accessed normally. The data may be recovered from storage media such as internal or external hard disk drives, solid-state drives (SSD), USB flash drive, storage tapes, CDs, DVDs, RAID, and other electronics. The recovery may be required due to physical damage to the storage device or logical damage to the file system that prevents it from being mounted by the host operating system.
Why is data recovery needed?
There are various reasons why data recovery is needed. The most common reasons include:
- Accidental deletion of files – Files may be accidentally deleted or formatted, requiring data recovery to retrieve them.
- Hardware failure – Failure of storage media like hard disk drives, SSDs, etc due to physical damage or logical errors.
- System crash – Operating system crash or failure may cause data on the hard disk to become inaccessible.
- Virus or malware attack – Virus or malware infection may corrupt files or affect the file system.
- Natural disaster – Floods, fires, earthquakes can physically damage storage media and cause data loss.
- Power failure – Sudden power failure during file transfer can cause data loss.
When critical data is lost due to any of the above reasons, data recovery is required to get back the lost files and information.
How does the data recovery process work?
The data recovery process involves multiple phases to retrieve the inaccessible data from the storage media. The main phases are:
1. Evaluation
The storage media is evaluated to determine the cause and extent of the data loss or failure. The evaluation helps identify the appropriate recovery method.
2. Recovery method selection
Based on the evaluation result, suitable recovery methods are identified to retrieve the data. Some common recovery methods are:
- Backup restoration – Restoring data from existing backup copies.
- Disk imaging – Creating disk image files to recover data from failing media.
- File system repair – Repairing corrupted file system structures.
- Data extraction – Directly reading data from disk platters or chip firmware.
- Repair tools – Using disk repair tools specific to different file systems.
3. Recovery process
The actual data recovery is done using the selected method. This may involve repairing the file system structures, extracting raw data from the disk, manually going through files, or other techniques based on the situation.
4. Data verification
The recovered data is checked for integrity and consistency. Missing file fragments are identified. Indexes are rebuilt to ensure directory structures and file mappings are correct.
5. Data restoration
The verified recovered data is transferred to another storage media or device as desired by the user. Additional file recovery attempts may be made if needed.
What kind of data can be recovered?
Almost all types of files can be recovered through data recovery as long as the storage medium is not completely damaged. Some examples of recoverable data are:
- Documents – Word documents, Spreadsheets, Presentations
- Media files – Photos, Videos, Audio files
- Archives – Zip, RAR archives
- Emails
- Database files
- Source code files
- System files
The likelihood of recovery depends on the severity of damage. Logical errors may be easier to recover from compared to physical damage.
What are the success rates for data recovery?
Data recovery success rates vary widely based on the type of data loss and extent of damage to the storage device. Some approximate success rates are:
| Data Loss Type | Success Rate |
|---|---|
| Accidental file deletion or format | 95% + |
| Logical Failure | 85% – 90% |
| Physical Failure | 50% – 80% |
| Natural Disaster/Fire Damage | 40% – 60% |
For logical failures like file system errors, virus attacks etc., the success rates are high. But for physical damage like disk head crashes, burnt circuits etc., recovery is difficult and success depends on the extent of damage.
What are the different types of data recovery?
Data recovery is broadly classified into the following types based on what needs to be recovered and how it is recovered:
1. Logical Data Recovery
Logical data recovery deals with recovering data lost due to logical errors like accidental format, file system corruption, virus attacks etc. The physical storage is intact, but the file system is damaged or data pathways are corrupted. File system structures are repaired to locate files.
2. Physical Data Recovery
Physical data recovery applies when the physical storage media itself is damaged due to head crashes, motor issues, burnt platters, etc. This requires extracting data directly from the disk platters and repairing damaged components.
3. Partition Recovery
Partition recovery recovers lost or deleted partitions when the partition table or boot sector is corrupted. It restores the original partition structure so data in the partitions can be recovered.
4. File Recovery
Single files may be corrupted or accidentally deleted. File recovery recovers important documents, pictures, videos, etc by scanning storage media and finding file signatures.
5. Email Recovery
Specialized email recovery tools are used to recover deleted or lost emails from email files based on file formats used by email clients.
6. Virtual Machine Recovery
VM recovery retrieves files from virtual disk (VMDK), disk image (VDI) files, or recovers configuration files of virtual machines.
7. Mobile Device Recovery
Mobile data recovery retrieves data from damaged or inaccessible Android phones, iPhones, tablet devices, etc. Specialized tools can crack locks and recover data.
8. Database Recovery
Database recovery rebuilds damaged database files of relational databases like SQL Server, Oracle, etc. Consistency checks and log files help ensure data integrity.
9. Backup Tape Recovery
Backup tape recovery is required when backup tapes become unreadable due to damage. Tape recovery specialists use specialized tools to retrieve data from the tapes.
What are the do’s and don’ts for data recovery?
Here are some important do’s and don’ts to increase chances of successful data recovery:
Do’s
- Stop using the storage device immediately after data loss.
- Handle storage devices carefully without any further damage.
- Use write protection wherever possible during recovery.
- Consult data recovery experts for physical recovery cases.
Don’ts
- Don’t attempt to recover data on your own unless you are an expert.
- Don’t run disk checking utilities like CHKDSK on failing drives.
- Don’t overwrite deleted data by adding more content.
- Don’t open the external enclosure of damaged portable disks.
How to choose a data recovery service?
Consider the following when choosing a data recovery service provider:
- Reputation & experience – Choose a reputable company with plenty of experience.
- Capabilities – Provider should be able to handle various storage devices and recovery cases.
- Security – They should offer secure handling of recovered data.
- Success rate – Check their past recovery success rate and quality.
- Pricing – Compare pricing between providers for the service required.
- Turnaround time – Faster turnaround is better for critical data recovery.
Go with established data recovery firms like Ontrack, DriveSavers, Gillware when possible. Be wary of suspiciously cheap offerings.
What are the costs involved in data recovery?
Data recovery costs depend on various factors, including:
- Type of damage
- Data recovery method
- Type of storage device
- Level of access difficulties
- Amount of data to recover
Logical recovery of deleted files may range from $300 to $1000. Physical recovery from hardware damage can cost $1000 to $2000 or more. Large enterprise-class recovery projects easily cost tens of thousands of dollars.
Some typical cost ranges are:
| Type | Cost Range |
|---|---|
| Hard disk drive recovery | $300 – $3000+ |
| RAID recovery | $1000 – $5000+ |
| SSD data recovery | $500 – $1500+ |
| USB flash drive recovery | $300 – $1000 |
| SD card recovery | $300 – $800 |
Many providers give free initial evaluation to assess feasibility and give a cost estimate. The cost may be adjusted later based on actual recovery process and data volumes.
How can data recovery be avoided in the first place?
While complete data loss avoidance is difficult, here are some best practices to minimize risks:
- Maintain regular backups – Backups allow restore of data if primary copies are lost.
- Handle storage media carefully – Physical damage can make recovery difficult/impossible.
- Ensure proper power handling – Use UPS/stabilizers to avoid electrical damage.
- Have recovery tools/boot environments ready – To quickly recover from system crashes.
- Proper access control – Prevent accidental/intentional deletion of files.
- Temperature control – Extremes of heat/cold can damage storage media.
- Analyze logs and alerts – To identify issues early before they cause data loss.
- Have a DR/BC plan – So processes are ready when data loss eventually occurs.
Planning for data recovery scenarios and having established systems and procedures can help minimize losses and speed up recovery when needed.
Conclusion
Data recovery allows retrieval of data lost due to logical errors, hardware failures, disasters, or human mistakes. Understanding the data recovery process, costs and planning for data recovery scenarios can help businesses minimize downtime and disruption when data loss occurs. With proper evaluation, method selection and controlled processes, skilled providers can often recover majority of lost data