RAID Controller Failure on NAS Synology DiskStation DS2415+: Causes, Recovery Approaches, and Consequences

Contents

• Why Regular Data Recovery Tools Can’t Restore Files from RAID
• Key Information About the NAS Synology DiskStation DS2415+
• 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 Synology 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 Synology DiskStation DS2415+ devices?

RAID configurations can significantly impact data loss in NAS Synology DiskStation DS2415+ devices. Here are a few ways RAID can affect data loss:

1. Redundancy: RAID configurations like 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 a disk failure. If one disk fails, the data can be rebuilt from the remaining disks. This reduces the risk of data loss due to hardware failures.
2. Hot Spare: Some RAID configurations support a hot spare disk, which acts as a standby disk that automatically replaces a failed disk in the array. This minimizes the downtime and reduces the risk of data loss during the disk replacement process.
3. Data Striping: RAID configurations like RAID 0 use data striping, where data is distributed across multiple disks to improve performance. However, RAID 0 does not provide redundancy, so if any of the disks fail, all the data on the array can be lost. It is important to note that RAID 0 should be avoided if data loss is a concern.
4. Rebuild Time: When a disk fails in a RAID array, the data from the failed disk needs to be rebuilt onto a new disk. The time taken for this rebuild process depends on the RAID configuration and the size of the disks. During the rebuild process, there is a higher risk of data loss if another disk fails. It is crucial to monitor the array and replace failed disks promptly to minimize the risk of data loss.
5. RAID Controller Failure: In some cases, the RAID controller itself can fail, leading to data loss. It is important to choose a reliable NAS device like Synology DiskStation DS2415+ that has a robust RAID controller and regular firmware updates to address any potential issues.

It is important to regularly backup data from NAS devices to an external location or use additional redundancy measures like offsite replication to further protect against data loss.

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

Although the NAS DiskStation DS2415+ 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 Synology DiskStation DS2415+. 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 Synology

DiskStation DS2415+ has 12 HDD slots, and it supports the following array types:

• Synology Hybrid RAID (SHR);
• RAID 6;
• RAID 5;
• RAID 10;
• RAID 1;
• RAID 0;
• Basic;
• JBOD;

NAS supports:

• Btrfs;
• EXT4;
• EXT3 (External Disk Only);
• FAT32 (External Disk Only);
• exFAT (External Disk Only);
• NTFS (External Disk Only);
• HFS+ (External Disk Read Only);

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 Synology DiskStation DS2415+ network-attached storage keeps DSM (DiskStation Manager) 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