Data Recovery Best Practices for NAS Promise Pegasus2 R4 RAID Arrays

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS Promise Pegasus2 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 RAID (Redundant Array of Independent Disks) configurations impact data loss in NAS Promise Pegasus2 R4 devices?

RAID configurations in NAS Promise Pegasus2 R4 devices can have a significant impact on data loss. Here are a few ways RAID configurations can affect data loss:

1. Redundancy: RAID configurations, such as RAID 1, RAID 5, or RAID 6, provide redundancy by distributing data across multiple disks. This redundancy helps protect against data loss in case of disk failure. If one disk fails, the data can be rebuilt or recovered from the remaining disks.
2. Fault tolerance: By using RAID configurations with parity data (such as RAID 5 or RAID 6), the NAS device can tolerate the failure of one or more disks without losing data. Parity data allows the system to rebuild the missing data from the remaining disks.
3. Hot spare: Some RAID configurations allow for the inclusion of a hot spare disk. A hot spare is a spare disk that is kept in the NAS device and can automatically replace a failed disk without manual intervention. This reduces the downtime and minimizes the risk of data loss.
4. Performance impact: Different RAID configurations have different performance characteristics. For example, RAID 0 offers improved performance but no redundancy, while RAID 5 or RAID 6 provide better redundancy but may have slightly lower performance due to parity calculations. Choosing the right RAID configuration based on your performance and redundancy requirements is crucial to avoid data loss.
5. Rebuild time: When a disk fails in a RAID configuration, the data from the failed disk needs to be rebuilt onto a replacement disk. The time it takes to rebuild the data depends on the size of the disks, the amount of data, and the RAID configuration. During the rebuild process, the system is vulnerable to additional disk failures, which could lead to data loss if not properly managed.

It is important to note that while RAID configurations can provide protection against disk failures and reduce the risk of data loss, they are not a substitute for regular backups. Having a comprehensive backup strategy is crucial to protect against other forms of data loss, such as accidental deletion, file corruption, or catastrophic events.

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

Although the NAS Pegasus2 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 Pegasus2 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

Pegasus2 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 Pegasus2 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