Data Recovery From A 6TB Synology NAS Device With Two Failed Hard Drives

Data recovery is a critical service in today’s data-driven world, where the loss of valuable information can have severe consequences. This case study details the complex recovery process undertaken by ACS Data Recovery to restore data from a failed 4-disk 6TB Synology NAS utilizing 2TB Seagate hard drives configured in RAID 5. The NAS experienced a catastrophic failure with two drives becoming completely inaccessible, one of which suffered from a severe head crash rendering it unrecoverable. This case study will highlight the meticulous steps taken by our expert team to recover the data, employing advanced tools and techniques while ensuring the highest standards of security and compliance.

Initial Assessment

Receiving the NAS and Diagnosing the Problem

Upon receiving the 4-disk Synology NAS, our first step was a thorough diagnostic assessment to understand the extent of the failure. The NAS was configured in RAID 5, which typically offers redundancy by using parity data. In this case, the RAID 5 configuration meant that the data could theoretically be rebuilt from the remaining drives, provided at least one of the failed drives could be sufficiently recovered.

Identifying the Failed Drives

The initial inspection revealed that two of the four Seagate 2TB drives were completely inaccessible. One of these drives exhibited a clicking sound, a classic symptom of mechanical failure. The other drive, although not clicking, was also unresponsive. The remaining two drives appeared to be operational but were not sufficient alone to recover the RAID array.

Detailed Diagnostic and Initial Recovery Attempts

Drive 1: Severe Head Crash and Platter Damage

The first failed drive, emitting the clicking noise, was disassembled in our Class 10 cleanroom. This drive exhibited a severe head crash, where the read/write heads had made contact with the platter surfaces, causing significant damage. The platters had deep gouges and visible scratches, which are indicative of catastrophic data loss.  While many times we can still get some data from situations like this; that was not possible due to the extent of the damage.  Platter material had been ground off most of the surfaces and the air filter was completely full of platter debris. Despite our best efforts, the damage was too extensive to recover any data from this drive.

Drive 2: Weak Read/Write Heads

The second failed drive was also disassembled in the cleanroom. This drive did not exhibit physical damage to the platters, but the read/write heads were found to be weak and unreliable. This diagnosis suggested that the heads could not read data reliably, but there was a possibility of recovery if the heads were replaced with a compatible set.

Head Replacement

Using our extensive inventory of donor parts, we sourced a compatible set of read/write heads. The head replacement procedure is highly delicate and requires precision and expertise. Our technicians successfully transplanted the new heads into the second drive. Post-replacement diagnostics showed the drive was operational, although in a degraded state. This was sufficient to proceed with data imaging.

Imaging the Drives

DeepSpar Disk Imager

To ensure the safety and integrity of the data during the recovery process, we used the DeepSpar Disk Imager. This tool is essential for creating cloned images of the drives, allowing us to work with copies rather than the original drives, thereby minimizing the risk of further damage.

Imaging the Operational Drives

The two operational drives were imaged first. DeepSpar Disk Imager’s advanced error handling capabilities allowed us to create clean, sector-by-sector clones of these drives with minimal data loss.

Imaging the Recovered Drive

The drive with the replaced heads posed a greater challenge due to its degraded state. We used DeepSpar’s adaptive imaging algorithms to handle the weak read/write heads, carefully adjusting read parameters to maximize the data recovered from this drive.  Initially we had problems with head 1, so we deactivated that head and imaged the remaining good heads.  We then reactivated head 1 and despite the degraded condition, we successfully imaged most of the drive.

Reconstructing the RAID Array

Analyzing RAID Parameters with WinHex

With cloned images of the three accessible drives, the next step was to determine the RAID parameters, including the drive order, block size, and parity distribution. WinHex, a powerful hex editor and disk analysis tool, was used for this purpose.

Calculating Parity and Drive Order

Using WinHex, we analyzed the cloned images to calculate the RAID 5 parity. By examining the data patterns and parity blocks, we determined the drive order and block size, which are critical for accurately reconstructing the RAID array. The analysis confirmed the RAID 5 configuration with a block size of 64KB.

Rebuilding the RAID Array

With the RAID parameters established, we proceeded to rebuild the RAID 5 array using specialized RAID recovery software. This process involved:

  1. Configuring the Virtual RAID Array: We set up a virtual RAID 5 array within the recovery software, using the cloned images of the three accessible drives.
  2. Reconstructing the MBR: The Master Boot Record (MBR) was reconstructed to ensure the logical structure of the array was intact.
  3. Regenerating the File System: The RAID recovery software then regenerated the file system, allowing us to access the data stored on the array.

Verifying Data Integrity

Initial Data Verification

To ensure the integrity of the recovered data, we performed a series of checks:

  1. File System Consistency: The regenerated file system was checked for consistency and integrity, ensuring no logical errors were present.
  2. File Sampling: We extracted several large JPG files and other significant data types to verify they were not corrupted. These files were opened and inspected for completeness and accuracy.

Comprehensive Data Recovery

Once the initial verification confirmed the integrity of the recovered data, we proceeded with the full data recovery:

  1. Extracting Data: All accessible data was extracted from the virtual RAID array. This included documents, images, videos, and other file types.
  2. Data Integrity Checks: Advanced data integrity checks were performed to ensure no files were corrupted or incomplete. This involved using checksum tools and file validation techniques.

Ensuring Data Security and Compliance

HIPAA Compliance

Given the sensitive nature of some of the data, it was crucial to ensure that our recovery efforts were secure and compliant with regulatory standards, including HIPAA. Our data recovery process adheres to strict security protocols, including:

  1. Secure Cleanroom Environment: All physical work on the drives was conducted in our Class 10 cleanroom, preventing any contamination which is also heavily restricted access to prevent data breaches.
  2. Data Encryption: Recovered data was encrypted during transfer and storage, ensuring it remained secure and inaccessible to unauthorized personnel.
  3. Confidentiality Agreements: All team members involved in the recovery process adhered to strict confidentiality agreements, safeguarding client privacy.

Secure Data Transfer

The recovered data was securely transferred to the client using encrypted storage devices. We provided detailed instructions on accessing and verifying the data, ensuring the client could restore their information securely and efficiently.


The recovery of data from a NAS in a RAID 5 configuration presented several challenges, including mechanical failures and severe platter damage. Despite the irreparable damage to one drive, ACS Data Recovery successfully restored the data by meticulously replacing the read/write heads on the second failed drive, imaging all accessible drives, and reconstructing the RAID array. Our use of advanced tools like the DeepSpar Disk Imager and WinHex, combined with our expertise and commitment to security and compliance, ensured a successful recovery.

This case study underscores the importance of professional data recovery services and the lengths to which ACS Data Recovery goes to retrieve critical data. Our high success rates and adherence to the highest standards of security and compliance make us a trusted partner in data recovery.  If you would like more information about our services or if you need data recovery, please don’t hesitate to call 1-800-717-8974.  We will be happy to help you out.