NAS RAID is used in the network attached storage devices. RAID is short for Redundant Array of Independent Disks, and has many advantages when properly configured in a NAS device. The benefits of NAS RAID include: prevent data loss due to hard drive failure; provide faster access to larger volumes; and allow dynamic data volume expansion without backup & restore. There are many RAID levels, and the levels in RAID have been gradually developed over a period of time. Different arrays are suited for different situations. Below is the brief introduction of RAID 1 and RAID 5.



Known as "mirroring", RAID 1 is the most basic RAID level aiming at protecting your data. NAS RAID 1 is the only redundant hard drive data protection available for two hard drives in home network storage devices. When either drive fails in a RAID 1 array, the other drive goes on to store and allow access to the data. However, there can be maximum two disks only. Other than write operations, RAID 1 is designed for faster read operations. The recovery of RAID 1 is only possible when only one of the two disks has failed. In the situation of using any modern multi-threaded operating system (Windows or Linux), RAID 1 array usually has a better performance for split seeks, which means access of same memory location by two different users. There is a need for a RAID 1 controller for each disk in the array for best performance.

Advantages of RAID 1:

  • A hundred percent of redundancy of the data.
  • No need to rebuilt data in case of a single disk failure.
  • Even though there are two disks in the array, the rate at which data gets transferred is that of a single disk.
  • Very easy to understand and execute.



RAID 5 is another common RAID hard drive arrangement found on the NAS devices. RAID 5 requires at least 3 hard drives, but you can add more to keep as backup. If any drive fails in a RAID 5 array, the system can rebuild the data as soon as that drive is replaced. This is based on the information stored on the other drives. The array is arranged so that failure of one disk can be kept hidden. But if the second disk fails before the replacement of the first one, there can not be any data recovery. When the first disk fails, the backup disk springs into action and data recovery is possible. In RAID 5, if a disk fails, it should be replaced as soon as possible. RAID 5 will typically be the minimum protection adopted in a small and medium-sized enterprise NAS device.

Advantages of RAID 5:

  • RAID 5 is built-in with load balancing mechanism.
  • Applications that perform the operation of random read work well on RAID 5.
  • High fault tolerance typically requires additional disk space. RAID 5 has high efficiency in that scenario.

The key to data loss prevention

Whether your network attached storage device is protected with RAID 1 or RAID 5, the key to data loss prevention is to replace the failed drive as soon as possible, so that the failures do not result in data loss due to the reduced level of NAS RAID protection. A precaution is by checking the status of the RAID protection to know if any drive had failed.

Some NAS devices have the ability to configure an email alert and even an indicator light on the front of the device to notify the responsible person that a drive has failed. Do make sure that any email alerts are properly configured to a valid email account and that the email will not be diverted to a SPAM folder.