When setting up a NAS (network attached storage) device, one of the first decisions you’ll need to make is whether to configure the drives in a RAID array. RAID (redundant array of independent disks) allows multiple drives to be grouped together for increased performance, capacity, or redundancy. However, RAID is not a requirement for NAS drives. There are both advantages and disadvantages to using RAID with a NAS that are important to consider.
What is RAID?
RAID is a technology that allows multiple physical hard drives to be grouped together into a single logical drive. The specific goals of a RAID array depend on the RAID level being used:
- RAID 0 stripes data across multiple disks for increased performance.
- RAID 1 mirrors disks for redundancy.
- RAID 5 stripes data across disks with parity for redundancy and performance.
- RAID 6 stripes data like RAID 5 but with double distributed parity.
- RAID 10 mirrors and stripes data across disks for increased performance and redundancy.
The key benefit of RAID is that it provides redundancy and/or improved performance compared to single disk configurations. If a single drive in a RAID array fails, the data can still be accessed from the remaining disks. Some RAID levels like RAID 0 offer a performance boost by spreading data across multiple disks that can be accessed in parallel.
Do NAS drives need to use RAID?
No, there is no requirement for NAS storage to use RAID configurations. Many consumer and small business NAS devices support JBOD (just a bunch of disks) configurations where the physical disks are available individually as separate logical drives.
The main advantages of not using RAID include:
- Simplicity – No special configuration required and disks can be easily added/removed.
- Low cost – No need to buy multiple matching drives to create a RAID array.
- Full capacity – No capacity overhead with parity or mirroring.
The downsides are:
- No redundancy – The failure of a single drive results in complete data loss for that drive.
- Limited performance – No performance improvements from striping/mirroring data across drives.
For home users or small businesses with few critical files, JBOD provides an affordable and easy NAS solution. But for storing important data, RAID provides protection against drive failures that is highly recommended.
RAID Configuration Options
If you do want to take advantage of RAID with a NAS, some of the popular RAID levels to consider include:
RAID 1
RAID 1 mirrors data across two or more drives. This protects against drive failure, but halves storage capacity. RAID 1 provides good performance for read operations but poor performance for writes. RAID 1 is a good option for storing critical data that needs redundancy. Two 4TB drives configured as RAID 1 would result in 4TB of usable storage.
RAID 5
RAID 5 stripes data across three or more drives with parity information spread across the drives. It provides redundancy while only losing 1 drive worth of capacity. With three 4TB drives, you would have 8TB of usable storage. Performance is good for both reads and writes. RAID 5 is a good balanced option that provides both redundancy and good usable capacity and performance.
RAID 6
RAID 6 is similar to RAID 5 but provides double distributed parity for even greater redundancy. In order to implement RAID 6, you need at least four drives. With four 4TB drives, you would have 8TB of usable storage. Performance is similar to RAID 5. RAID 6 is recommended for very large storage arrays where drive failures are more likely.
RAID 10
RAID 10 combines mirroring and striping by creating mirrored drive pairs and then striping data across the pairs. This provides both high performance and redundancy. With four 2TB drives, you would have 4TB of usable storage. RAID 10 is great option for applications that demand higher performance but still require redundancy. The capacity loss compared to RAID 5/6 may be a downside for large arrays.
Hardware vs. Software RAID
RAID can be implemented either through a dedicated hardware RAID controller or via software RAID provided by the operating system.
Hardware RAID uses a dedicated RAID card with its own processor and memory to manage the RAID array. Software RAID relies on the CPU and system resources to perform the RAID calculations.
Hardware RAID advantages:
- Higher performance – Dedicated controller optimizes RAID operations
- Increased reliability – RAID management is independent of OS or drive errors
- Extra features – Robust management interfaces, caching, battery backups, etc.
Software RAID advantages:
- Lower cost – No need for a dedicated RAID card
- Easier management – Configured through the operating system
For NAS solutions, hardware RAID and software RAID both have merits. For higher performance NAS systems, a hardware RAID card is recommended. But for home and small business users, software RAID provides an affordable way to implement RAID.
RAID vs. Backups
It’s important to understand that RAID is not a backup solution. RAID manages the redundancy of drives that are actively being used for primary storage. But RAID cannot protect against catastrophic failures that damage the system itself like fires, floods, malware, or user error.
To properly protect your NAS data, you should implement both RAID for redundancy of active storage as well as external backups, either cloud based or using removable media. RAID will minimize downtime in the event of a single or even multiple drive failures. But only a backup can allow you to recover from larger disasters affecting the entire NAS.
The 3-2-1 backup rule provides a good guideline:
- 3 copies of your data (primary NAS storage and 2 backups)
- Using 2 different media types (local and cloud storage)
- With 1 copy stored offsite (cloud or removable storage)
Sample NAS RAID Configurations
Here are some examples of recommended RAID configurations for NAS solutions depending on use case:
Two drive home NAS
For a simple two-bay NAS for home use, RAID 1 using two 4TB drives provides redundancy while still delivering 4TB of usable storage. The performance will be better than a single drive and a drive failure can be tolerated.
Four drive NAS for media storage
For a small business NAS for shared media storage, four 4TB drives in a RAID 5 provides the best overall value. Usable capacity is maxed out at 12TB with the redundancy to handle a single drive failure. Performance will also see improvements over JBOD or RAID 1.
Eight drive NAS for high demand applications
For demanding applications like video editing or virtualization that require both higher performance and redundancy, eight 2TB drives can be configured as two RAID 10 arrays (four drives each). This would result in 4TB of usable capacity that can withstand two drive failures with the performance benefits of RAID 10 over RAID 5/6.
Twelve drive NAS for maximum capacity
To maximize the storage capacity on a 12 bay NAS while still providing redundancy, 12x 4TB drives can be configured as a RAID 6 array. This results in 36TB of usable storage with the ability to withstand up to two drive failures. Performance will be reduced compared to RAID 10 but meets the capacity requirements.
Synology Hybrid RAID
Many NAS systems like Synology offer what they call Hybrid RAID (SHR). This allows mixing drive sizes in a RAID array and starting with just one drive. SHR is essentially Synology’s version of standard RAID types like RAID 1 or RAID 5. The benefit is flexibility – you can combine whatever drives you have on hand and expand the array as needed. The disadvantage is potentially poorer performance compared to a properly planned RAID array using matched drives. But for home users, SHR provides a good balance of flexibility and redundancy.
UnRAID
UnRAID is another option that has become popular for home NAS builds. It is a proprietary RAID system that allows combining mismatched drives of any size. UnRAID provides redundancy by designating one drive as a parity drive. Data is spread across the remaining data drives. UnRAID offers advantages like mixing drive sizes, expanding arrays 1 drive at a time, and allowing dual parity for additional redundancy. The main downside is poorer parity drive performance for write operations. UnRAID is a good option for media storage but may not suit more demanding applications.
ZFS and Other File Systems
The RAID configuration is only one piece of the NAS storage puzzle. The file system used on the RAID array also plays a huge role in determining the overall performance, redundancy, and features available. Some popular NAS file systems include:
- ZFS – Robust file system with redundancy, snapshots, and powerful integrity checks
- Btrfs – Also provides snapshotting and data integrity checks
- EXT4 – Standard Linux file system without some advanced NAS features
For example, ZFS brings additional data integrity checks using checksums, as well as advanced snapshotting and storage pooling capabilities. This helps enhance the underlying RAID protection and provides more ways to recover from data loss events. Selecting the right combination of RAID configuration and NAS file system ties all the components together into a comprehensive storage strategy.
Conclusion
In summary, while RAID is not strictly required for a NAS deployment, some form of RAID can provide very worthwhile benefits including:
- Increased storage performance
- Redundancy and protection against drive failures
- Additional options like snapshots and integrity checking with advanced file systems
The optimal RAID setup depends on your priorities for capacity, performance, and budget. RAID 1, 5, 6, and 10 are common configurations that each optimize these factors differently. UnRAID and Synology Hybrid RAID also present unique alternatives. To protect against larger failures and disasters, proper backups are still a requirement even with RAID in place. But implementing the right RAID solution can provide a critical line of defense against drive failures and downtime.