RAID Knowledge Base

RAID systems can be configured for use as a backup drive. Software running on a computer or server manages the backups, and files are copied to a RAID which is directly attached or connected to a network as a NAS device.

Because RAID systems have more than one drive and use redundancy, there is a common belief that data is protected and doesn't require a secondary backup. But, while redundancy provides some safety against data loss, there is no protection if more than one drive fails.

RAID level 0 (striping) spreads blocks of data across multiple drives, which help increase performance. It offers speed, but of all the levels of RAID, it is the most susceptible to potential data loss.

Because data is divided into segments and distributed across the drives when one device fails, all data could be lost. Fortunately, Ontrack has over 35 years of experience and has developed hundreds of custom software utilities to address the most challenging data recovery work.

Hopefully, you have a backup of the RAID data, which would allow you to restore critical files quickly. If you don't have a backup here are some tips to help:

• Test a rebuild when the RAID is functional to ensure you have it properly configured and the management software installed.
• Review the RAID documentation and learn how to handle drive failures and rebuilds when you first install the system. If you read the documentation after a failure, you might be too stressed, which can lead to mistakes that can make the data unrecoverable.
• If you don't have a clear understanding of how the device crashed or the hardware failed, call Ontrack for professional help.

Whether you are setting up a RAID to attach directly to a computer or connecting a NAS on a network, choosing a level of RAID depends on your requirements for performance and data safety. There are multiple levels of RAID, and each uses a specific method for data storage. Some of the most common RAID levels are:

RAID 0 (striping) divides data into separate blocks that are distributed over your storage devices. It provides the fastest retrieval to your files because drive access time is reduced. You need a minimum of two drives to use RAID 0.

RAID 1 (mirroring) creates an identical copy of all of your data onto another drive (or multiple drives). This helps protect the data should one of the drives fail, but you should always have a separate backup of your data in case both drives fail simultaneously—which does happen.

RAID 5 (striping with parity) requires a minimum of 3 drives and offers one of the safest RAID levels. With RAID 5, data is distributed along with parity data, which adds redundancy allowing the RAID to be rebuilt when one of the drives fails.

RAID (Redundant Array of Independent Disks) contains multiple drives and attaches directly to a computer system. Used primarily for file storage, RAID is perfect for handling large files required by video editors and audio engineers.

NAS (Network Attached Storage) is an appliance that connects via a network and provides file-sharing services. A NAS may contain multiple drives configured with RAID software, or simply contain a single drive.

You can easily recover all your deleted or formatted data from the RAID drives. Once you rebuild the RAID, you can select and scan the drives or the virtual RAID drive. Once the scan is completed, select the files you want to recover from the scanned list. Then select ‘Recover’, choose the destination, and click ‘Start Saving’.

Most of the time, data is recoverable after reformatting a RAID 5 volume, depending upon the way you in which it is reformatted. In the Windows operating system data is still recoverable if we reformat and create an empty volume. The original data still exists on the drive in the ‘Free and Available’ space. However, when a low-level format, is performed by the RAID controller utility it completely wipes every single block on a drive overwriting any data in the free space. A low-level format is slower than a high-level format.

A RAID system can fail, and data becomes inaccessible due to:

• RAID controller failure
• Multiple RAID hard drive failures
• Intermittent drive functionality resulting in RAID degradation
• Accidental reformatting of drives or the entire RAID array
• Failed rebuild or lost RAID array configuration
• Immediate RAID server crash due to power issues
• Application or software corruption

It is possible to recover deleted data from a RAID server with Ontrack EasyRecovery Toolkit. Run the software and recover all your important data. In addition, the software provides the option to recover data from virtual RAID construction as well.

To efficiently recover data from a RAID array you need all the member RAID drives. Besides, the drives should be in the proper sequence.