Best Practices for Data Recovery from a NAS Promise Vess 1740i RAID Array Failure

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS Promise Vess 1740i
• 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 a NAS Promise Vess 1740i device's cache settings impact data loss risks?

The cache settings on a NAS Promise Vess 1740i device can impact data loss risks in the following ways:

1. Write Cache: The write cache is used to temporarily store data before it is written to the underlying storage disks. Enabling write cache can improve write performance, but it also introduces a risk of data loss in case of power failure or system crash. If the write cache is not flushed to the disks before such events occur, the data in the cache may be lost.
2. Read Cache: The read cache stores frequently accessed data to improve read performance. While read cache does not directly impact data loss risks, it may affect data integrity if the cache becomes inconsistent with the underlying disks. If the NAS device experiences disk failures or data corruption, the read cache may serve outdated or corrupted data, leading to potential data loss or data inconsistency.
3. Battery Backup Unit (BBU): Some NAS devices, including the Promise Vess 1740i, offer a BBU to protect the write cache. In case of power failure, the BBU provides temporary power to flush the write cache to the disks, ensuring data integrity. Enabling the BBU can significantly reduce the risk of data loss related to the write cache.
4. Cache Synchronization: The NAS device may have settings to control the synchronization between cache and disks. It is crucial to ensure that the cache is synchronized with the disks to minimize the risk of data loss. If the synchronization is not performed regularly or properly, data inconsistencies or loss can occur.

To mitigate data loss risks, it is recommended to:

• Enable the BBU if available to protect the write cache.
• Regularly backup critical data to an external storage device or off-site location.
• Monitor the health of the storage disks and RAID arrays to detect and address any potential issues promptly.
• Implement a reliable power supply and backup power solutions to minimize power-related risks.
• Regularly update the NAS firmware and drivers to ensure bug fixes and security patches are applied.
• Follow best practices and manufacturer guidelines for cache settings and synchronization to maintain data integrity.

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

Although the NAS Vess 1740i 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 Vess 1740i. 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

Vess 1740i has 16 HDD slots, and it supports the following array types:

• RAID 0;
• RAID 1;
• RAID 1E;
• RAID 3;
• RAID 5;
• RAID 6;
• RAID 30;
• RAID 50;
• RAID 60;
• 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 Vess 1740i 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