RAID 10, also known as RAID 1+0, is a hybrid RAID configuration that combines disk mirroring and disk striping to provide increased performance and fault tolerance compared to other RAID levels. But does RAID 10 actually improve performance compared to a single disk or other RAID configurations?
In short, yes – RAID 10 can provide significant performance improvements over a single disk or RAID 1. By striping data across multiple mirrored disk pairs, RAID 10 allows for parallel reads and writes, increasing overall throughput and I/O operations per second (IOPS). The performance boost depends on several factors like disk speed, controller cache, and workload type.
How does RAID 10 work?
RAID 10 requires a minimum of 4 drives and combines mirroring and striping by first mirroring data across pairs of drives, then striping the mirrored data across the drive pairs in chunks. This provides fault tolerance from the mirrors and performance from the stripes.
For example, with 4 drives, data would be written to the first and second drives simultaneously while also being written to the third and fourth drives. Data is then read in parallel stripes across the mirrored drive pairs, enabling increased IOPS.
Advantages of RAID 10
- Increased read/write performance – data is striped across multiple drives
- Fault tolerance from mirroring – data remains accessible if one drive fails in a mirrored pair
- Ideal for transactional workloads requiring fast random reads/writes
- Balances performance and redundancy
RAID 10 Performance vs Single Disk
Compared to a single disk, RAID 10 can provide significant gains in read and write performance by distributing load across multiple disks. Some advantages versus a single disk:
- Increased overall IOPS and throughput since reads/writes occur in parallel
- Faster response times for random reads and writes
- Ability to sustain multiple concurrent read and write operations
- Higher total bandwidth with multiple disk channels
For example, 4 SATA drives in RAID 10 can provide up to 400-500 IOPS random read, while a single SATA drive may only provide 75-100 IOPS, depending on its spec. For large sequential workloads, RAID 10 can provide up to 4X the throughput of a single drive.
RAID 10 vs Single Disk – Sample Performance
| Configuration | Random Read IOPS | Random Write IOPS | Sequential Read | Sequential Write |
|---|---|---|---|---|
| Single SATA SSD | 5,000 | 3,000 | 500 MB/s | 350 MB/s |
| 4-drive RAID 10 SATA SSD | 20,000 | 12,000 | 2,000 MB/s | 1,400 MB/s |
As this sample data shows, RAID 10 can provide major gains in both random and sequential performance over a single drive configuration, with 4X the IOPS and bandwidth in some cases.
RAID 10 vs RAID 1 Performance
Compared to RAID 1 disk mirroring alone, RAID 10 also provides performance benefits from the additional disk striping:
- Higher IOPS from spreading reads/writes across more disks
- Increased bandwidth since data is striped in parallel
- Lower average read/write latency
- Better performance for random mixed workloads
In general, RAID 10 can deliver 2X the read IOPS versus RAID 1 in a 4-drive configuration, along with gains in overall throughput. By reading/writing in parallel to the additional stripe, RAID 10 reduces latency and improves mixed workload performance.
RAID 10 vs RAID 1 – Sample Performance
| Configuration | Random Read IOPS | Random Write IOPS | Sequential Read | Sequential Write |
|---|---|---|---|---|
| 4 drive RAID 1 | 150 IOPS | 150 IOPS | 480 MB/s | 420 MB/s |
| 4 drive RAID 10 | 300 IOPS | 250 IOPS | 960 MB/s | 840 MB/s |
This comparison of 4 drive configurations shows RAID 10 providing gains in both random and sequential performance over RAID 1 mirroring alone while also offering fault tolerance.
When does RAID 10 offer the most benefit?
RAID 10 excels in certain workloads and use cases where high performance is critical:
- Transactional databases – provides fast response for random reads/writes
- Virtualization and VDI environments
- High performance web/app servers
- Video editing and media production
- Small critical data sets needing performance and redundancy
The performance gains of RAID 10 are most beneficial for transactional, random I/O workloads that require low latency like databases. RAID 10 is ideal for virtual servers and performance-driven applications.
Workloads where RAID 10 helps less
RAID 10 advantages are less pronounced on workloads dominated by large sequential I/O:
- Video surveillance and media streaming
- Big data analytics and data warehousing
- Bulk file storage and archives
For these sustained sequential workloads, the higher cost of RAID 10 may make it less ideal versus RAID 5 or RAID 6.
RAID 10 performance factors
Several factors impact the real-world performance gains from implementing RAID 10:
- Disk speed – Faster disks (SSDs or high RPM HDDs) provide bigger gains
- Workload – Random transactional workloads benefit most
- Controller cache – Bigger cache improves read performance
- Number of drives – More drives increase IOPS and bandwidth
- Stripe size – Bigger stripes improve sequential throughput
Optimizing these factors for your workload is key to getting the most performance from a RAID 10 array. High performance disks combined with a controller with ECC cache will maximize gains.
Tuning RAID 10 for performance
Tips for tuning RAID 10 for better performance:
- Use the fastest disk types suitable for your budget – SSDs are ideal
- Add drive counts in multiples of 2 for more mirroring pairs
- Ensure controller has a battery-backed cache
- Optimize stripe size for more sequential throughput
- Benchmark performance for your actual workloads
What are the downsides of RAID 10?
Disadvantages to weigh when considering RAID 10:
- Higher cost than RAID 5 or RAID 6 for larger arrays
- Only provides the capacity of a single drive in the mirror
- Rebuilding array takes longer than RAID 5/6 due to mirroring
- More complex to setup and manage than other RAID levels
While RAID 10 delivers performance, it comes at higher cost as more physical drives are required compared to parity-based RAID. Capacity efficiency is also lower compared to RAID 5 or 6 since RAID 10 only uses 50% of total drives for storage.
Alternatives to RAID 10
- RAID 5 – More space efficient than RAID 10, but slower writes
- RAID 6 – Double parity provides high redundancy for large arrays
- RAID 50/60 – Nested RAID combines RAID 5/6 with striping
- JBOD – Just a Bunch of Disks provides large pooled capacity
For users requiring maximum capacity along with performance, consider nested RAID levels like RAID 50 or RAID 60 which stripe RAID 5 or RAID 6 arrays. JBOD is an option for large archives.
Conclusion
RAID 10 delivers substantial gains in performance over a single disk or RAID 1 mirroring by combining striping and mirroring. The parallel I/O across multiple striped mirrored pairs provides major benefits for transactional and random workloads. However, RAID 10 comes at a higher cost versus RAID 5 or 6 and requires planning to optimize for specific workloads. For critical applications needing both speed and redundancy, RAID 10 is an excellent choice.