Best Practices for Recovering Data from a Failed NAS Promise Pegasus2 M4 RAID Configuration

Contents

• Why can’t ordinary software tools restore files from RAID?
• How to take hard disks out of the NAS and connect them to a PC?
  • Restoring data with Hetman RAID Recovery
  • Safe recovery from disk images
  • Where are user’s files stored?
  • Comparison of software for RAID recovery

Why can’t ordinary software tools restore files from RAID?

Conventional hard disks keep user’s data by writing it to their surface in a consecutive way, and this is how an entire file is stored on a single hard disk. However, when data is written to a RAID system, a file is divided into several parts. Then these parts are written consecutively to all hard disks within such array. The size of such parts may range from 2 KB to 2 MB, so each file is stored on several hard disks at the same time.

Such approach helps to speed up read and write operations, and it is evident that saving two parts of a file having the size of 1 GB to two hard disks simultaneously is much faster than saving the same 1 GB of data to one hard disk. However, this peculiarity makes file recovery more complicated.

Various RAID levels store information in different ways. Additionally, manufacturers like Promise also introduce some modifications to this process, and that is why data can be written to hard disk in a wide variety of ways.

How can storage tiering or caching strategies impact data availability and potential loss on NAS Promise Pegasus2 M4 devices?

Storage tiering and caching strategies can have a significant impact on data availability and potential loss on NAS Promise Pegasus2 M4 devices. Here are a few ways in which these strategies can affect data availability and potential loss:

1. Improved Performance: By implementing storage tiering and caching strategies, you can improve the overall performance of your NAS device. Caching allows frequently accessed data to be stored in faster storage media, such as solid-state drives (SSDs), resulting in faster read and write speeds. This improves data availability by reducing latency and ensuring quick access to frequently accessed data.
2. Data Redundancy: Storage tiering can also help in ensuring data redundancy. By using a combination of different storage media, such as SSDs and hard disk drives (HDDs), you can create redundant copies of critical data. In the event of a drive failure, the redundant copy can be used to maintain data availability and prevent potential loss.
3. Data Protection: Caching strategies, such as write-back caching or write-through caching, can impact data protection. Write-back caching temporarily stores write operations in cache before writing them to the permanent storage. While this improves performance, there is a risk of potential data loss if a power outage or system failure occurs before the data is written to the permanent storage. On the other hand, write-through caching immediately writes data to the permanent storage, ensuring data durability but potentially affecting performance.
4. Capacity Optimization: Storage tiering helps optimize storage capacity by automatically moving less frequently accessed data to slower storage tiers. This frees up space on faster storage media for frequently accessed data, improving performance. However, there is a risk of potential data loss if the tiering algorithm is not properly configured or if there is a failure in the tiering process.
5. Backup and Recovery: Storage tiering and caching strategies should be considered in the context of backup and recovery. While these strategies can improve performance and data availability, they should not be considered a substitute for regular backups. It is essential to have a robust backup strategy in place to protect against potential data loss caused by hardware failures, software errors, or other unforeseen events.

In summary, storage tiering and caching strategies can have a positive impact on data availability and performance on NAS Promise Pegasus2 M4 devices. However, careful planning, configuration, and monitoring are necessary to mitigate the potential risks of data loss and ensure the overall reliability and resilience of the storage system.

How to take hard disks out of the NAS and connect them to a PC?

Although NAS Pegasus2 M4 can be accessed over the network, you still need to take the hard disks out of the storage device and connect them to a Windows computer. Only in this case will the software be able to scan them properly. Here is what you should do:

1. Turn off the storage and disconnect it from the power supply.

   WARNING! Before you start taking hard disks out of your NAS device, read the manual carefully. Incorrect actions may damage your network-attached storage and/or the hard disks within the RAID system.

2. Take the hard disks out of the NAS one by one, carefully removing them from their slots. Remember that the disks are extremely vulnerable: hitting or dropping them may result in serious physical damage.

3. Make sure to mark each hard disk in accordance with how they were installed inside the NAS.

4. Remove the hard disks and connect them to the computer. In this video, we have explored what ports are used to connect hard disks, and what to do if there are not enough ports or connectors.

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   How to Order Remote Data Recovery

Restoring data with Hetman RAID Recovery

This program recovers data from damaged RAID arrays and is fully compatible with Promise Pegasus2 M4. The hard disks that make up the RAID contain technical information about the algorithm used to save files. When launched, Hetman RAID Recovery reads this information and puts the damaged array together. Then you can open the disk and save your files. Also, you can recover the files accidentally deleted from the network drive.

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How to recover data from a Promise

Pegasus2 M4 has 4 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;

Safe recovery from disk images

This utility lets you save an entire copy of the disk to file and then work with this image instead of the actual disk. Such feature helps to protect data on the disk from:

• Overwriting during the recovery process;
• Loss resulting from bad sectors;
• User mistakes.

To create an image, do the following:

1. Make sure that you have enough free space to save the image. The image file size usually equals the disk size.

2. Select the disk in the main window, and choose from the menu Tools – Save Disk. You can select multiple disks to be saved.

3. When the image creation wizard starts, you can choose to save the entire disk or select only a part of it. Specify the parameters and click Next.

   

4. At this stage, you need to choose a directory where to save the image. Choose any disk connected to this PC, or save the image by FTP.

   

Where are user’s files stored?

The Promise Pegasus2 M4 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.

Comparison of software for RAID recovery