Best Practices for Recovering Data from NAS Promise Pegasus R4 RAID Array Failures

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS Promise Pegasus R4
• How to Remove Hard Disks from Your NAS and Connect Them to a PC
  • Step-by-Step Data Recovery with Hetman RAID Recovery
  • How to Safely Recover Data from Disk Images
  • Where Are the User’s Files Actually Stored?
  • RAID Recovery Software: Detailed Comparison

Why Regular Data Recovery Tools Can’t Restore Files from RAID

Conventional hard drives store user data by writing it sequentially across the disk surface, which means an entire file is typically located on a single drive. In contrast, when data is written to a RAID array, each file is split into multiple fragments. These fragments are then distributed and written in sequence across all the drives in the array. Depending on the configuration, fragment sizes can range from 2 KB to 2 MB, so every file is physically stored across several disks at once.

This approach significantly increases read and write performance — after all, writing two halves of a 1 GB file to two drives simultaneously is much faster than writing the full 1 GB to a single disk. However, this same mechanism makes file recovery far more complex.

Different RAID levels use different methods to distribute and protect data. On top of that, manufacturers like Promise often add their own proprietary structures and variations. As a result, data can be written to disks in many different formats, and each requires a specific approach during recovery.

How can regular data verification or checksum processes help maintain data integrity on NAS Promise Pegasus R4 devices?

Regular data verification or checksum processes can help maintain data integrity on NAS Promise Pegasus R4 devices in the following ways:

1. Detecting and preventing data corruption: Regular data verification processes involve comparing the checksum of the data being read with the stored checksum value. If the checksums don't match, it indicates that data corruption has occurred. By performing these verifications regularly, you can identify corrupted data early and take appropriate actions to prevent further damage.
2. Ensuring accurate data storage: Checksum processes generate a unique value based on the data being stored. This value is stored alongside the data. When retrieving the data, the checksum is recalculated and compared with the stored value. If they match, it ensures that the data has been accurately stored and retrieved without any modifications.
3. Identifying hardware or software issues: Regular data verification processes can help identify any underlying hardware or software issues that may be causing data corruption. If you consistently encounter checksum mismatches, it may indicate problems with the storage device, cables, or even the NAS system itself. By addressing these issues promptly, you can prevent further data integrity problems.
4. Preventing silent data corruption: Silent data corruption refers to the situation where data gets corrupted without any indication or error message. By regularly performing data verification or checksum processes, you can proactively identify silent data corruption and take corrective measures before it leads to data loss or other critical issues.
5. Enhancing data recovery capabilities: In case of data loss or corruption, having regular data verification processes in place can improve the chances of successful data recovery. By comparing the checksums of the corrupted data with the known good checksums, you can identify which portions of the data are corrupted and attempt to recover them from backups or other sources.

Overall, regular data verification or checksum processes provide an additional layer of protection and help ensure the integrity of data stored on NAS Promise Pegasus R4 devices.

How to Remove Hard Disks from Your NAS and Connect Them to a PC

Although the NAS Pegasus R4 can be accessed over the network, you still need to remove its hard disks and connect them directly to a Windows PC. Only then can the recovery software properly scan and analyze the drives. Follow these steps:

1. Power off the NAS and disconnect it from the power source.

   WARNING! Before removing any drives, carefully read the device manual. Improper actions may damage both the NAS enclosure and the hard disks in the RAID array.

2. Remove the hard disks one by one, gently sliding each drive out of its slot. Remember that hard disks are highly sensitive: any impact or drop can cause serious physical damage.

3. Label each hard disk according to its position inside the NAS. The order of the drives is crucial for correct RAID reconstruction.

4. Connect the drives to your computer. In this video, we explain which ports you can use to connect hard disks and what to do if your PC does not have enough free connectors.

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   How to Order Remote Data Recovery

Step-by-Step Data Recovery with Hetman RAID Recovery

This program restores data from damaged RAID arrays and is fully compatible with Promise Pegasus R4. Each hard disk in the array contains technical metadata describing how files were written. When launched, Hetman RAID Recovery analyzes this metadata, automatically reconstructs the damaged array, and provides access to its contents. After that, you can browse the recovered disk and save your files. The program can also restore files that were accidentally deleted from the network drive.

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How to recover data from a Promise

Pegasus R4 has 4 HDD slots, and it supports the following array types:

• RAID 0;
• RAID 1;
• RAID 1E;
• RAID 3;
• RAID 5;
• RAID 6;
• JBOD;

NAS supports:

• exFAT, VFAT, FAT 12 / 16 / 32;
• NTFS / ReFS;
• APFS / HFS+;
• Ext2 / 3 / 4 / ReiserFS / XFS / UFS / ZFS / Btrfs;
• VMFS / HikvisionFS;

How to Safely Recover Data from Disk Images

This utility allows you to create a complete copy of a disk and work with the disk image instead of the physical drive. This approach helps protect your data from:

• Overwriting during the recovery process;
• Additional data loss caused by bad sectors;
• User errors.

To create a disk image, follow these steps:

1. Ensure you have enough free space to store the image. Its size will typically match the size of the original disk.

2. In the main window, select the target disk and choose Tools - Save Disk. You can also select multiple disks if needed.

3. When the Image Creation Wizard opens, select whether you want to save the entire disk or only a specific region. Adjust the settings and click Next.

   

4. Choose the directory where the image will be saved. You may select any available disk connected to your PC or upload the image via FTP.

   

Where Are the User’s Files Actually Stored?

The Promise Pegasus R4 network-attached storage keeps OS Linux operating system files on a separate RAID 1 (mirrored) array. Usually, all NAS systems create several volumes on every hard disk, and the first of them takes up to 2 Gb of space. This is where operating system files are stored. Other volumes are united into a RAID array where user’s data is written.

RAID Recovery Software: Detailed Comparison