Best RAID for NAS

Best RAID Configuration for your NAS

Network Attached Storage devices are becoming more and more popular. They’re a great way to store and access your files, no matter where you are. NAS devices have hard drives inside them that can be accessed either by the computer it’s connected to or any computer on the network.

In the world of storage, NAS (Network Attached Storage) is king. NAS provides a great alternative to a cloud-based storage solution. There are many factors that go into choosing the right NAS for your needs.

A typical NAS (Network Attached Storage) device is used to provide file sharing capabilities for one or more users on a network. Choosing the right RAID level is crucial to maximizing storage efficiency and the performance of a NAS device.

This blog post will examine four common RAID levels that may be used with a NAS device, including RAID 0, RAID 1, RAID 5, and RAID 10.

What is RAID?

RAID stands for Redundant Array of Independent Disks and is a technique for combining multiple disks of the same type into a logical unit. This way, data can be read or written to different disks in parallel, speeding up the process.

RAID is a way to distribute data in a way that minimizes the chances of data loss and protects against hardware failure. There are different types of RAID, each with their own purpose and number of disks needed to implement it. What RAID level should you use with your NAS?

Before we dive into answering this question, let’s take a closer look at each RAID level in detail.

Commonly used RAID Levels

As outlined in the introduction, we are going to look at the most commonly used RAID levels. including RAID 0, RAID 1, RAID 5, and RAID 10 (or RAID 1+0).

There are two broad ways you can implement a RAID. They are software-based RAID and hardware-based RAID.

  • In software-based RAID, the operating system manages the RAID configuration which requires system over-head.
  • In hardware-based RAID, the motherboard must support it out-of-the-box or additional hardware is purchased. Hardware-based RAID will always outperform a software RAID because it’s done at the hardware level.

Each RAID level comes with its own set of pros and cons, so careful consideration needs to be taken in order to choose the right RAID level for your needs.


RAID 0 is often referred to as striping, disk striping or striped volumes. It does NOT provide fault tolerance of any kind as data is distributed across 2 or more disks and is not duplicated in any way.

The big advantage to RAID 0 is speed. With 2 disk forming a RAID 0, read/write speed can be effectively doubled, however, it is not exactly double the speed.

The reason the speed is not increased by a factor of 2x is because of the system overhead needed to manage the disk array.

RAID 0 Example
Image source: CompTIA A+ Training Kit

If you were to add yet another set (2 disks) to this array you can see an almost 75% increase in read/write speed compared to 1 single disk.


RAID 1 uses two disks only and is known as disk mirroring. As the name implies, this RAID level uses redundancy or “mirroring” to preserve data integrity.

Therefore, a RAID 1 configuration is single fault tolerant, in that, if one of the disk drives fail the data in the other drive is preserved.

RAID controllers will then be able to “rebuild” the failed disk drive once a new one is installed and may even “fail-over” to the single drive until this happens so there is no interruption.

While having single fault tolerance is great, there are a few drawbacks to RAID 1 configurations:

  • You don’t get the additional disk storage of adding the second disk. Example, having two 500 GB disk drives = 1 TB will only appear to the operating system as 500 GB.
  • With a RAID 1 configuration there are no speed benefits on the ability to write a file to disk.
  • The entire file has to be written to a single disk and then mirrored to the second disk which takes time.

While it is true there are no speed enhancements when writing a file to disk, some speed gains can be observed reading the file because the RAID controller knows the file exists on two different disks. Therefore, it can read from both disks in parallel.

RAID 1 Example
Image source: CompTIA A+ Training Kit


RAID-5 uses at least three disks and is commonly referred to as striping with parity. It uses the equivalent of one disk drive for parity (method of error detection) to provide fault tolerance.

To demonstrate how RAID-5 parity works examine the following table:

RAID 5 Parity Example
Image source: CompTIA A+ Training Kit
  • In a RAID 5, a group of bits are combined with parity in a stripe. For example, the row for 3 includes three bits in the stripe: 1 and 1 for data and 1 for parity.
  • Parity is set to “0” or “1” to ensure the stripe has an odd number of 1 bits.

RAID 5 does not write data one bit at a time, instead it writes in 64 KB stripes. While it uses the equivalent to one drive for parity, it is not contained on just one drive. It is in fact spread out across all three drives holding the parity in different stripes.

RAID 5 Parity Striping on Multiple Disks
Image source: CompTIA A+ Training Kit

RAID 5 can have more than three drives, it can have five or even six drives. That said, it still allocates the equivalent of one drive for parity.

For example if there were five drives in the RAID-5 array, one drive would be for parity, and four drives for data.

RAID 10 (1+0)

RAID 10 is made up of a combination of RAID 1 (mirrored) and RAID 0 striped disks. It is often referred to as a stripe of mirrors and includes at least four disk drives.

It offers superior performance and fault tolerance over the other RAID’s discussed, however, it is the most expensive of the four.

The image below shows an example of how this works:

  • Disks 1 and 2 are a RAID 1 (mirror) and they each hold a copy of the same data.
  • Disks 3 and 4 create another RAID 1 (mirror) and they each hold a copy of the same data.
  • Combined Array A and Array B are configured as a RAID 0 stripe.
  • Disks in the mirror labeled Array A hold half the data, and Disks in the mirror labeled Array B hold half the data.
RAID 10 Example
Image source: CompTIA A+ Training Kit

RAID 10 has superior read/write performance, similar to RAID 0, and fault tolerance similar to RAID 1.

Additionally, RAID-10 can survive the failure of multiple disk drives. For example, if Disk 1 fails in Array A and Disk 3 fails in Array B then you can still operate from Disks 2 and 4.

However, if two disk drives fail in the same mirror, time to look for your backups!!!

Available Disk Storage for each RAID Level

Now that you have a firm understanding of what each RAID level is and the benefits and drawbacks they provide. Let’s look at a practical example.

The table below provides examples for a given RAID configuration and number of disk drives, how much usable space will you have if the disk drives have a capacity of 500 GB each?

RAID Disk Storage Requirements
Image source: CompTIA A+ Training Kit

Which RAID is Best for a NAS Device?

Now the million dollar question, which RAID is best for a NAS device? At this point the answer should be evident that it depends on the level of fault tolerance you need, the amount of money you have to spend and the amount of storage you require.

If you don’t really care about fault tolerance (redundancy) or speed enhancements and are just looking to have a storage device sitting on your network, then you can pick up a 1-bay NAS device such as the Synology DS118 DiskStation.

On the other hand if you are looking to have at least single fault tolerance (RAID 1), or are seeking a performance boost that 2-disks can offer in a RAID 0 configuration, then you’ll want to choose a NAS storage device that has at least 2 bays in it.

Again, we are big advocates of Synology NAS devices, so for this job and budget we recommend you check out the DiskStation DS220+. This is a great NAS device for your personal or small home office needs.

One word of warning, when purchasing a NAS device be aware that many of them do not come with the hard disk drives (HDDs) included. These are often a separate purchase.

It is always recommended to use identical HDDs in RAID configurations. For top-performing NAS disks, check out the Seagate IronWolf HDDs specifically designed for NAS devices.

Notwithstanding what’s been mentioned, if both fault tolerance and speed are a necessity for you, then implementing a RAID 5 or even a RAID 10 configuration is optimal. Keep in mind, in order to implement these RAID levels you will need to move to more specialized (and more expensive) NAS storage solutions.

To get you started with a solution that can support a RAID 5 or RAID 10 configuration, have a look at the Synology DiskStation DS920+.

Final Words…

We hope we’ve shared some useful information with you today. Finding the best RAID for NAS configuration is largely going to depend on your requirements. If you enjoyed this article, consider sharing it in your social feeds.

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