NAS Storage Raid Levels: Which one is right for you and Why?

Introduction

Network Attached Storage (NAS) devices like Synology are extremely popular for home and business use due to their centralized storage, shared access, and flexibility. Firstly, the key feature of NAS storage systems is the ability to configure (RAID: Redundant Array of Independent Disks) RAID levels for optimized performance, capacity, and fault tolerance.

But with so many NAS Storage Raid levels to choose from, how do you determine the right setup for your needs?

What is covered:

Explaining, What is RAID and why does it matter?
Detail on RAID 0, 1, 5, 6, and 10 options
Performance, redundancy, and capacity comparisons
Matching RAID levels to example usage scenarios
Best practices for selecting and configuring RAID

What is NAS Storage Raid Levels and Why Does it Matter?

RAID is a technology that allows you to use multiple hard disk drives together as if they were a single drive. Moreover, arranged in a RAID array, and configured using the NAS operating system, this are top-class drives.

RAID delivers increased performance, capacity, and reliability through different mechanisms of striping (spreading data across drives) and mirroring (duplicating data identically on multiple drives).

The major goals of RAID are to:

Improve performance – read and write speeds are increased by distributing data across multiple disks
Prevent data loss – duplication and parity allow reconstruction of data if drives fail
Increase capacity – total available storage space scales with the number of drives

Without RAID, your NAS would see each hard drive as an individual unlabeled volume. Furthermore, It allows the disks to work together so the intelligent data storage across the array is possible.

Some key advantages of RAID include:

Speed – data can be read and written faster in parallel versus using a single disk
Capacity – total storage space to multiply with additional drives
Availability – failed drives are replaceable without data loss in redundant configurations
Flexibility – RAID levels is changeable as needs evolve

Besides that, the right RAID setup depends on your priorities – whether that’s maximizing speed, maintaining redundancy, or optimizing available capacity. We’ll now dive deeper into the most common RAID levels.

RAID 0 Overview

RAID 0 (also called disk striping) spreads data evenly across all drives with no redundancy. RAID 0 breaks up data into blocks and stripes the blocks sequentially across each drive in the array.

The benefit of RAID 0 striping is that disk performance is maximized since data is written and read in parallel across multiple drives simultaneously. Additionally, total usable capacity is also maximized since there is no space reserved for parity or mirroring.

Ideal RAID 0 Use Cases

Some example RAID 0 use cases include:

Scratch disk – Video editing scratch disk handles lots of temporary I/O that benefits from maximum speed
Non-critical data – Storing expendable data like downloads or caches that require high speed but no redundancy
Maximum capacity – Apps needing largest possible disk space like data lakes or archives

RAID 0 Pros

Fastest reads and writes – spreading I/O over multiple disks improves parallelism
Low cost per GB – uses full combined capacity
Simple to implement

RAID 0 Cons

No redundancy – single drive failure results in total data loss
Increased array failure risk – more drives means a higher chance of failure
Rebuilding array reinitializes all disks

Overall, RAID 0 is ideal when high sustained performance and maximum capacity are required, while redundancy is less important. The tradeoff is increased risk of catastrophic data loss if any part of the array fails.

RAID 1 Overview

RAID 1 (disk mirroring) duplicates data across paired drives in the array. If one drive fails, an exact copy of the data is available on the mirror drive. Moreover, RAID 1 is the simplest RAID levels to understand and implement.

Mirroring provides excellent read performance since either drive can service the request, doubling read speed. Additionally, writes are duplicated to both drives, so write performance is slower than single disk but faster than parity RAID.

Total usable capacity with RAID 1 is 50% of the total raw capacity, since duplicates are maintained. At least 2 drives are must for RAID 1.

Ideal RAID 1 Use Cases

Example RAID 1 uses:

Small NAS – 2-4 bay NAS systems benefit from easy RAID 1 redundancy
Databases – Transactional data requires fast mirrored writes
Critical data – Important files and data require duplication

RAID 1 Pros

Simple mirroring redundancy
Fast reads – doubles read performance
Only 2 drives minimum required

RAID 1 Cons

50% storage efficiency
Slow writes compared to single disk
No incremental capacity and redundancy scaling

RAID 1 remains a popular choice for smaller NAS deployments, prioritizing redundancy over storage capacity. Additionally, the 2 drive minimum makes it ideal for typical 2-4 bay consumer NAS devices.

RAID 5 Overview

RAID 5 strips data and parity information evenly across all member drives. The distributed parity enables the array to reconstruct data in the event of a single drive failure. If a drive fails, the missing data can be calculated using the parity bits on the remaining disks.

At least 3 physical disks are must for a RAID 5 array. Compared to mirroring in RAID 1, usable capacity is significantly higher as only a single drive worth of capacity is used for parity. Overall, this provides an efficient combination of redundancy and storage.

Ideal RAID 5 Use Cases

Example uses for RAID 5:

General purpose NAS – Good mix of capacity and redundancy for home/SMB NAS
Media storage – Large media files still benefit from single drive redundancy
Backups – Provides redundancy without mirroring overhead

RAID 5 Pros

Efficient redundancy with only 1 parity disk
Strong read performance with striping
Incremental scalability when expanding array

RAID 5 Cons

Slow writes due to parity calculation
No protection against multiple drive failures
Rebuilding array is slow after replacement

Lastly, the balance of usable capacity and single drive fault tolerance makes RAID 5 a popular choice for general purpose NAS storage.

RAID 6 Overview

Well, RAID 6 improves upon RAID 5 by using a second independent set of parity data, enabling survival from up to two disk failures. Dual disk fault tolerance provides an extra layer of redundancy for large arrays.

At least 4 physical drives are required for a RAID 6 array. With two drives worth of capacity used for parity, total usable space is lower compared to RAID level 5. But RAID 6 can sustain up to two failed drives with no data loss.

Ideal RAID 6 Use Cases

Example uses for RAID 6:

Large NAS arrays – Larger number of drives increases chance of dual failure
Media production – Guard against dual drive loss with critical project data
Archival storage – Provides redundancy for large amounts of archived data

RAID 6 Pros

Survives up to 2 drive failures
Incremental expansion of large arrays
Strong read performance

RAID 6 Cons

Slow write performance due to dual parity
Less overall usable capacity vs RAID 5
Rebuilding after failure takes longer

For most home and SMB users, RAID 5 provides sufficient redundancy. However, RAID 6 becomes advantageous for large scale and enterprise NAS deployments where the likelihood of dual drive failure is higher over long time periods.

RAID 10 Overview

This RAID 10 combines aspects of RAID 0 striping and RAID 1 mirroring. Moreover, it requires a minimum of 4 drives, arranged as mirrored pairs where each mirrored set is then striped.

This provides the redundancy of RAID 1 along with the performance of spreading reads and writes across multiple disks. RAID 10 can withstand drive failures in each mirror set. Lastly, total usable capacity is 50% of raw capacity, the same as RAID 1.

Ideal RAID 10 Use Cases

Example RAID 10 uses:

Transactional databases – Provides fast redundant writes for databases
Virtualization – Handles the demanding I/O of virtual servers and storage
High performance – Applications needing high speed and redundancy

RAID 10 Pros

High read and write throughput
Mirrored redundancy for each stripe set
Incremental expansion with disk pairs

RAID 10 Cons

50% storage efficiency
Minimum 4 drives required
Rebuilding array requires re-mirroring

The performance and redundancy of RAID 10 comes at the cost of high disk overhead. But for applications that demand speed along with fault tolerance, RAID 10 is an excellent choice.

RAID Level Performance Comparison

Let’s compare the relative read and write performance among the main RAID levels:

RAID 0 offers the fastest overall read and write speeds by striping data in parallel across multiple disks.
Well, the RAID 10 read performance approaches RAID 0 due to striping across mirrored sets. Writes are slower than RAID 0 due to mirroring overhead.
Next, RAID 5 and RAID 6 have asymmetric performance – reads are faster than writes due to parity calculation on writes. RAID 6 has lower write performance than RAID 5 due to dual parity.
RAID 1 has excellent read speed by reading in parallel from both mirrors but slower writes due to duplicating.

In most cases, any striped RAID level will provide better read performance than a single disk. Writes are generally faster on RAID 0/10 versus parity based RAID 5/6.

RAID Level Redundancy Comparison

The amount of disk failure protected against also varies among RAID levels:

RAID 0 provides no redundancy – any disk failure results in total data loss
To withstand failure of any one disk in a mirrored pair, RAID 1.
RAID 5 survives loss of any single disk due to parity protection
Where as, RAID 6 provides additional protection against dual disk failures
RAID 10 can survive failures in each mirrored stripe set

If redundancy is paramount, RAID 6 provides the highest fault tolerance followed by RAID 10 and RAID 1. RAID 5 provides good redundancy for typical scenarios. RAID 0 should only be used where redundancy is not required.

RAID Level Capacity Comparison

The amount of total storage capacity available differs as well depending on mechanisms used for redundancy:

RAID 0 stores data across all disks for 100% capacity
Next, RAID 1 duplicates data to both mirrors, 50% usable capacity
RAID 5 reserves 1 disk worth of space for parity, (N-1)/N capacity
Moreover, RAID 6 uses 2 disks for parity, (N-2)/N capacity
RAID 10 mirrors each stripe set, 50% usable capacity

RAID 0 provides maximum capacity but no redundancy while RAID 1 and RAID 10 sacrifice half of total space for mirroring. When it comes to, RAID 5 provides good usable capacity with single parity. Besides that, RAID 6 requires more disks to maximize usable space due to dual parity overhead.

Best Practices for Selecting a RAID Level

Now that we’ve compared the options in depth, let’s discuss some best practices for choosing the right RAID level for your NAS:

Consider your redundancy requirements – If redundancy is unimportant, RAID 0 provides maximum performance and capacity. For robust redundancy, choose RAID 6 or RAID 10.
Evaluate disk performance vs usable capacity – RAID 0 provides all capacity with fastest performance. RAID 1 and 10 offer maximum redundancy but sacrifice capacity and write speeds.
Factor in drive counts – RAID 1 only requires 2 drives while RAID 6 needs a minimum of 4. RAID 10 provides redundancy with fewer drives than RAID 6.
Benchmark performance tests – Test potential RAID configurations with your actual workload if possible. This provides real data on expected speeds.
Standardize on RAID 5 or RAID 6 – For most SMB NAS uses, RAID 5 or RAID 6 offer a good blend of redundancy and capacity.
Plan for future expansion – Consider future NAS expansion needs and choose a RAID level like 5 or 6 that allows incremental disk additions.
Monitor drive health – Keep an eye on disk smart stats and replace failing drives early to avoid rebuilding failed arrays.

Matching RAID Levels to Usage Scenarios

To make RAID selection more concrete, here are some examples of choosing appropriate RAID levels for different usage scenarios:

Home media NAS – RAID 5 provides good capacity for large media files while still guarding against drive failure. RAID 6 provides extra redundancy for very large arrays.

2-bay NAS – The 2-drive minimum makes RAID 1 with mirroring a good option for extra redundancy on small 2-4 bay consumer NAS devices.

Network backups – For network storage of backup images, RAID 5 offers a balance of redundancy and storage density to provide ample backup capacity.

Virtual machine host – For a NAS hosting virtual machine storage, RAID 10 can provide the performance to handle demanding VM I/O while also protecting against disk failure.

High traffic database – Transactional databases requiring high redundancy and performance makes RAID 10 ideal for fast mirroring and striping.

Scratch disks – RAID 0 maximizes speed for video editing scratch disks by spreading reads and writes over multiple disks. A lack of redundancy is acceptable for temporary scratch data.

Archival storage – Large amounts of archived data can take advantage of RAID 6 redundancy while maximizing usable storage density for the archive.

Conclusion

Configuring the RAID for your Synology NAS lays the essential groundwork for your storage performance, redundancy, and capacity. While the array of options provides flexibility, it can also induce choice paralysis.

Moreover, by taking the time to understand the core strengths of each RAID type, you can zero in on the best fit for your needs and priorities.

For most home and SMB users, RAID 5 or RAID 6 provides an optimal blend of usable space, speed, and single or dual-drive fault tolerance. But, specific use cases may benefit from the specialized capabilities of RAID Levels such as 0, RAID 1, or RAID 10.

Regardless of your RAID selection, proper ongoing maintenance, like monitoring drive health and rebuilding failed arrays quickly, is critical.

With the foundation of your ideal RAID in place, your Synology NAS can serve as a high-performance, resilient storage platform ready to evolve with your data needs over time.

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