What is RAID 1?

Written By: Ontrack

Date Published: 6 November 2023 2:18:01 AM

What is RAID 1?

Healthy RAID 1 Array

The system for better fault management.

While the RAID system overall makes it possible to optimise data storage by distributing it over several hard disks, each configuration has its own advantages.

RAID 1, which mirrors data, is especially recommended for those who are primarily looking for redundancy.


What is a RAID 1 configuration?

A RAID array is a collection of multiple disks that are configured either by software or a hardware controller in a certain way to protect data or enhance performance. RAID stands for a redundant array of independent disks. There are many different types of RAID arrays which affect read and write speeds as well as redundancy or fault tolerance.

The RAID 1 system is probably one of the simplest. It works on the principle of mirroring. In other words, the disks in the array are organised in pairs. On each pair, the information is written simultaneously. In short, RAID 1 has perfect redundancy, which benefits data security.


Can RAID 1 be used on an external hard drive?

RAID technology is usually used on an internal hard disks, but it is quite possible to apply this RAID system to external hard disks. There are commercially available enclosures specifically designed to accommodate multiple hard drives that allow for the creation of a RAID 1 array.


Can we have a NAS server in RAID 1?

The answer is yes. As a reminder, a NAS or Network Attached Storage is a stand-alone storage unit. It is essentially a share that is accessible through your network (private or professional). You can configure the storage on your NAS in a variety of RAID configurations, including RAID 1.


Can you recover data from a RAID 1array?

A healthy RAID 1 array will have 2 drives mirrored, meaning the data is the same across both drives.

Healthy RAID 1 Array

RAID 1 systems allow for the recovery in a couple different ways. If the primary disk in the array fails, the system should fail over to the secondary member. This allows the user to continue to use the system without interruption. The failed drive can then be replaced with a new drive and remirrored to the secondary drive.

If that failover doesn’t work, or both drives report failures, Ontrack can assist. Using our advanced clean room technologies, the Ontrack team will attempt to image both drives.

If one of the drives images without errors, the Ontrack team will use that data to rebuild the logical volume and recover the data. In the image below, Ontrack would use Drive 1 to rebuild the file system and recover the data.

RAID 1 Array with One Failed Drive

If both drives image with errors, the team can use data from both drives to rebuild the logical file system and recover your data.  Having 2 drives to pull data from gives the Ontrack a great chance to recover all of your files.  In the image below, Ontrack would use parts of Drive 1 and parts of Drive 2 to rebuild the file system and recover the data.  Data stripes 1 and 4 would come from Drive 1 and data stripes 2 and 3 would come from Drive 2.

RAID 1 Array with Two Failed Drives


KLDiscovery Ontrack Pty Ltd, Suite 9, 28 Donkin Street, West End, Brisbane, QLD 4101, Australia (see all locations)