NAS or Network Attached Storage is an advanced data storage solution wherein multiple drives can be configured either as a single storage pool or as a RAID array. Users prefer using a RAID-based NAS storage setup as it provides higher data availability and data redundancy (depending on RAID level) to protect against data loss due to drive failure.
As there are various RAID configurations to choose from, many users find it difficult to select a suitable RAID level to configure with NAS. In this guide, we will explain the factors that you can look for when choosing RAID configuration for NAS.
What are the Most Common RAID Levels?
RAID configuration or level refers to the setup used to organize multiple drives so they can work together as a single logical storage unit. Each RAID level has its own characteristics and features. Tabulated below are the details of some commonly used RAID levels.
| RAID Level | RAID 0 | RAID 1 | RAID 5 | RAID 6 |
| Min. No. of Drives Required | 2 | 2 | 3 | 4 |
| Data Storage Technique | Striping | Mirroring | Striping + Single Distributed Parity | Striping + Double Distributed Parity |
| Fault Tolerance | None | 1 drive failure | 1 drive failure | 2 drives failure |
| Hot Swapping | No | Yes | Yes | Yes |
| Performance | High read/write speed | High read speed | High read speed, slow write speed | High read speed, slow write speed |
| Number of Usable Drives | 2 drives | 1 drive | D = (n-1) drives; 1 drive for single parity | D = (n-2) drives; 2 drives for double parity |
| Ideal For | Individuals or home users | Individuals or home users | Small businesses | Small/Medium businesses |
How to Select the Best RAID Configuration for NAS?
When selecting a suitable RAID level for your NAS, there are various factors to consider – read/write speed & performance, number of bays, usable storage capacity, type of drives to be used, fault tolerance, and cost of setup. Let’s read more about these factors in detail.
Read/Write Speed and Performance
Every RAID configuration offers different features – high data availability, improved read/write (R/W) & performance, or data redundancy & resilience. For example, RAID 0 offers improved read speed and delivers raw performance as it stripes the data into smaller blocks and stores it linearly on the member drives. RAID 1, on the other hand, delivers high read speeds and lower write speeds as it simultaneously uses all the member drives to read and write data.
In RAID 5 and RAID 6 setups, the data is striped across the drives, which helps strike a balance between read and write speeds. In addition, these configurations provide data redundancy that makes the setup resilient against disk failures – RAID 5 (1 drive failure) and RAID 6 (2 drive failure).
Usable Storage Capacity
The storage space you can use to save data on a RAID array changes based on how you set it up. Take RAID-0 as an example. It doesn’t use extra space for parity or to protect your data. This means you get to use all of the storage space. Some RAID types – RAID 5 and RAID 6 – have overhead (parity), which takes up additional storage space on the drives. Hence, the usable storage capacity decreases accordingly.
Let’s understand how this concept works with different RAID levels with an example. Let’s say you have a 4-bay NAS setup with 4x 2TB HDDs that you want to configure as RAID. The table below shows how much usable storage you’ll get with different RAID types:
| RAID Type | Usable Storage | Protection |
| RAID 0 | 8TB | 0TB |
| RAID 1 | 2TB | 6TB |
| RAID 5 | 6TB | 2TB |
| RAID 6 | 4TB | 4TB |
Number of Drive Bays
NAS is quite a flexible storage solution as you can easily configure member drives as RAID within the same hardware. However, the type of RAID configuration you can select for NAS depends on the number of bays present in the enclosure.
- 2-bay NAS: RAID 0 or RAID 1 would be the only configurations to use as these require a minimum of 2 disks.
- 3-bay NAS: Apart from RAID 0 and RAID 1, with a 3-bay NAS, you can also setup RAID-5 as it requires a minimum of 3 disk drives.
- 4-bay NAS: A 4-bay NAS enclosure is ideal to set up RAID 5 as it will have enough usable storage while keeping some space aside for calculating data overhead. It also supports RAID 6 configuration – requiring a minimum of 4 disk drives.
- 6-bay NAS: With a 6-bay NAS enclosure, you can configure any RAID type – 0, 1, 5, or 6 – with ease.
Budget and Cost of Setup
When it comes to cost, configuring a RAID array (with fewer drives) in a smaller NAS box would be economical. But, if you have a large enclosure, the cost will be obviously higher to set up the RAID. Moreover, the price to set up a RAID array in a NAS is also determined by the type of storage drives you will choose. HDDs are comparatively cheaper than SSDs.
Fault Tolerance
Parity plays a crucial role when choosing a RAID configuration as it helps recover data in case of a disk failure. But not all RAID levels offer protection against drive failure. RAID 0 has no fault tolerance and hence a single drive failure could result in complete array failure and data loss. RAID 1, on the other hand, creates mirror copies of the primary drive on secondary drive/s. This allows the array to sustain a single drive failure. RAID 5 and RAID 6 arrays have single-distributed and double-distributed parity. This helps the arrays to sustain a single disk and double disk failure, respectively.
Is RAID-based NAS Prone to Failure and Data Loss?
A RAID-based NAS is not completely prone to failure and data loss. Though data redundancy and fault tolerance is available in several RAID levels, there are various factors and reasons that could result in RAID/NAS failure and data loss. Listed below are some common reasons:
- Dissimilar drives used while setting up RAID (capacity, brand, etc.)
- Improper or abrupt shutdown of the system
- Multiple disk failure
- RAID-controller failure
- Hardware failure
- Firmware corruption
- NAS OS crash
So, you should implement additional measures to ensure complete data protection or recover data after drive failure. You can keep a specialized NAS data recovery software handy that can help in recovering data from a RAID-based NAS in case of a data loss threat or other reason. Stellar Toolkit for Data Recovery is one such tool that can recover all kinds of data, such as files and folders, media files, etc., from an inaccessible RAID-based NAS device. It can recover lost or accidentally deleted data from SSH-enabled or offline Synology, ASUSTOR, and QNAP NAS devices, and other storage media, such as HDDs, SSDs, flash drives, CDs/DVDs, and more.
Watch this video to learn how to perform NAS data recovery using this software.
Bottom Line
As explained above, choosing a RAID configuration for NAS requires you to consider several factors, such as read/write speed, amount of usable storage capacity, number of bays in the NAS box, fault tolerance, and others. You can go through these factors that choose the best RAID configuration for NAS as per your requirements.
Though some RAID configurations offer data redundancy and fault tolerance, this is not enough to provide complete data protection. Therefore, you should keep a professional NAS data recovery software, like Stellar Toolkit for Data Recovery in hand. This all-in-one tool can help recover deleted or lost files from your RAID-based NAS without any hassle.
