RAID (Redundant Array of Independent Disks) is a data storage technology that combines multiple disk drive components into a logical unit. RAID provides increased storage functions and reliability through redundancy. There are different RAID levels that provide various combinations of performance, redundant reliability, and efficiency. RAID 10, also known as RAID 1+0, is considered one of the best RAID levels for most applications due to its excellent combination of data protection and speed.
What is RAID 10?
RAID 10 combines RAID 1 (disk mirroring) and RAID 0 (disk striping) for increased performance and fault tolerance. In RAID 10, data is written in stripes across primary disks and secondary mirror disks simultaneously. This results in fast data transfers from the striping of RAID 0 and the fault tolerance of mirrored disks in RAID 1.
Specifically, RAID 10 requires at least four disks. Data gets written in stripes across two primary disks in a RAID 0 array. That RAID 0 array gets mirrored onto two additional disks, creating the RAID 1 array. This configuration provides extremely fast read and write speeds from the RAID 0 striping along with the redundancy of RAID 1 mirroring.
How Does RAID 10 Provide Speed and Redundancy?
RAID 10 excels at providing both speed and redundancy through its combination of RAID 0 and RAID 1.
The striping in RAID 0 writes data across multiple disks simultaneously. By spreading data across multiple disks, input/output operations per second (IOPS) gets maximized. However, RAID 0 alone provides no redundancy. If one disk fails, all data gets lost.
RAID 1 alone mirrors data across disks, providing complete data redundancy. But RAID 1 does not provide the performance boost from striping in RAID 0. A RAID 1 array can only perform operations as quickly as a single disk.
By combining both RAID 0 and RAID 1, RAID 10 provides fast IOPS performance from striping in RAID 0 and redundancy from mirroring in RAID 1. Data gets written to multiple disks for speed and copied to redundant disks for protection. This makes RAID 10 ideal for applications requiring both high performance and fault tolerance.
Benefits of RAID 10
RAID 10 provides excellent benefits that make it the best RAID level choice for many implementations:
High Speed Reads and Writes
The RAID 0 striping used in RAID 10 allows concurrent reads and writes to multiple disks for very fast data transfers. By spreading data across multiple disks, the workload also gets distributed to avoid bottlenecks.
Fault Tolerance
RAID 10 provides complete data redundancy through RAID 1 mirroring. If a disk fails, the mirrored disk can instantly take over without any data loss or downtime. RAID 10 can withstand multiple disk failures so long as one disk in each mirrored pair remains functional.
Fast Rebuilds
RAID 10 rebuilds mirrored drives very quickly. Only the affected mirror needs to be rebuilt, not the full array. Quick rebuilds minimize the risk of a second disk failure during rebuild and restore full redundancy quickly.
Read Performance During Rebuild
Unlike other RAID levels, RAID 10 maintains its high read performance even during drive rebuilds. Reads can be serviced from the unaffected mirror disk while the failed drive rebuilds in the background.
Smaller Transfer Blocks
RAID 10 uses smaller data transfer blocks than other RAID levels. Small transfer blocks optimize performance for random access workloads in applications like databases.
Write Consistency
RAID 10 writes data to both the striped array and the mirror consistently. Other RAID levels write to the parity drive inconsistently. The consistent writes in RAID 10 provide better performance and reliability.
Drawbacks of RAID 10
While RAID 10 has many advantages, there are some drawbacks to weigh when considering its use:
High Cost
RAID 10 is expensive since it requires a minimum of four disk drives. The cost for entry is higher than other RAID options with fewer disks.
Less Total Storage
The mirroring in RAID 10 cuts the total usable storage in half when compared to a single disk. RAID 10 provides the total storage of the smallest mirrored pair. For example, two 1TB and two 2TB drives would result in 1TB total storage.
Not Optimized for Large Files
Large sequential writes do not benefit as much from striping. Large files like videos, backups, or archives may have slower write times compared to other RAID levels better optimized for large sequential writes.
When to Use RAID 10 – Best Applications
RAID 10 works best for applications that require high random read/write performance and maximum fault tolerance. The speed and redundancy make it ideal for scenarios including:
Database Servers
Databases require very fast IOPS performance and high availability. The small transfer blocks and fast rebuilds of RAID 10 work extremely well for heavy database workloads.
Read-Intensive Applications
RAID 10 provides top read performance, even during rebuilds. Any application requiring consistently fast read speeds will benefit from RAID 10.
Virtualized Servers
Virtual environments demand high IOPS and low latency. RAID 10 excels at providing consistently fast speeds for demanding virtualized workloads.
Mission-Critical Systems
For systems requiring maximum uptime, RAID 10 provides the necessary redundancy to minimize downtime. The fast rebuilds also restore redundancy quickly.
Small to Medium Businesses (SMBs)
SMBs often have more limited budgets but still require performance and reliability. RAID 10 can provide enterprise-class data protection without excessive cost.
RAID 10 Performance Benchmarks
Here are some benchmarks demonstrating the excellent performance of RAID 10 in real-world applications:
Database Transactions per Minute
| RAID Level | Transactions Per Minute |
|---|---|
| RAID 10 | 6820 |
| RAID 6 | 4350 |
For database workloads, RAID 10 provides significantly more transactions per minute compared to RAID 6.
Virtual Machine IOPS
| RAID Level | Average IOPS |
|---|---|
| RAID 10 | 9120 |
| RAID 5 | 6750 |
The higher IOPS performance of RAID 10 results in much faster response times for virtual machines versus RAID 5.
Rebuild Times
| RAID Level | Rebuild Time |
|---|---|
| RAID 10 | 3 hours |
| RAID 6 | 9 hours |
Rebuilding a failed drive takes 3x longer in RAID 6 than RAID 10. The faster rebuilds of RAID 10 minimize downtime.
Choosing the Right RAID 10 Setup
There are several RAID 10 configuration options to consider for optimal performance in specific applications:
Drive Counts
RAID 10 requires a minimum of four drives but can scale beyond that. Four drives allow for a single drive failure. Eight drives can tolerate three drive failures. Determine the level of fault tolerance needed.
Drive Speeds
SSD drives provide faster performance than HDDs. But SSDs are more expensive. Using SSDs for the primary striped array and HDDs for the mirrors may provide a cost-effective balance.
Hardware vs. Software RAID
Hardware RAID with dedicated RAID controllers allows the RAID processing to be offloaded from the CPU for better efficiency. But hardware RAID is less flexible. Software RAID uses the host computer’s resources but can be configured on any system.
Comparing RAID 10 to Other RAID Levels
RAID 10 has distinct advantages over other RAID levels that make it stand out for certain use cases:
Vs. RAID 0
| RAID 10 | RAID 0 | |
|---|---|---|
| Data Redundancy | Yes | No |
| Fault Tolerance | Excellent | None |
| Minimum Disks | 4 | 2 |
Unlike RAID 0, RAID 10 provides fault tolerance and redundancy. But both offer fast speed from striping.
Vs. RAID 1
| RAID 10 | RAID 1 | |
|---|---|---|
| Data Redundancy | Yes | Yes |
| Read Speed | Very Fast | Fast |
| Rebuild Speed | Very Fast | Fast |
RAID 10 and RAID 1 both mirror data. But RAID 10 adds striping for faster performance.
Vs. RAID 5
| RAID 10 | RAID 5 | |
|---|---|---|
| Disk Failures Tolerated | 1 per RAID 1 pair | 1 disk |
| Read Speed During Rebuild | Unaffected | Degraded |
| Rebuild Time | Fast | Slow |
RAID 10 rebuilds faster with less impact during failure versus RAID 5. But RAID 5 requires fewer disks.
Conclusion
RAID 10 provides an excellent blend of performance and fault tolerance that makes it the top choice for applications requiring speed along with redundancy. The combination of RAID 0 striping and RAID 1 mirroring balances cost-effectiveness with enterprise-class protection. With its high IOPS, fast rebuilds, redundancy, and consistency, RAID 10 is one of the best overall RAID levels for critical business systems.