RAID 10, also known as RAID 1+0, is a hybrid RAID configuration that combines disk mirroring and disk striping to protect data and optimize performance. Configuring RAID 10 requires at least 4 drives and provides increased data protection and read/write speeds compared to RAID 1 or RAID 0 alone.
What is RAID 10?
RAID 10 is a nested RAID level that uses both mirroring and striping across drives for redundancy and performance. It requires a minimum of 4 drives configured as 2 mirrored pairs where data is written in stripes across the mirrored spans. This provides fault tolerance up to 2 drive failures, as long as no more than 1 drive in each mirrored pair fails.
Benefits of RAID 10
- Increased read performance – data can be read in parallel from multiple drives
- Increased write performance – data is written in stripes across multiple drives
- Fault tolerance – Up to 2 drive failures are tolerated without data loss
- Ideal for transactional workloads requiring fast I/O
RAID 10 Configurations
RAID 10 can be configured in several ways depending on the number of drives:
- 4 drives – 2 mirrored pairs striped (minimum required)
- 6 drives – 3 mirrored pairs striped
- 8 drives – 4 mirrored pairs striped
- 10 drives – 5 mirrored pairs striped
Generally, you want an even number of drives that can be broken into mirrored pairs and striped. More drives allow for increased performance.
Hardware and Software Requirements
To configure RAID 10, you will need:
- RAID controller – supports RAID 0 and 1 configurations
- 4 or more compatible physical drives – matching models and capacities recommended
- RAID configuration software/utility – check controller documentation
Most hardware RAID controllers support RAID 10. For software RAID, you need an operating system like Windows, Linux, etc. with RAID capabilities. The RAID utility will depend on your specific platform.
Supported RAID Controllers
Common RAID controllers that support RAID 10:
- LSI MegaRAID
- Dell PERC
- HP Smart Array
- Adaptec Series 8
- Intel RAID
Check your controller documentation for RAID level support. Most modern hardware RAID controllers support RAID 10.
Compatible Drives
You need at least 4 physical drives to create a RAID 10 array. More drives can enhance performance. All drives in the array should be:
- Same capacity for simplicity
- Same rotational speed (all SSD or all HDD)
- Same model for consistency
Using mismatched drives can degrade performance or cause issues. For best results, use identical drives.
RAID 10 Configuration Steps
Follow these general steps to configure RAID 10:
- Check RAID controller and determine RAID utility
- Install at least 4 compatible physical drives
- Enter the RAID configuration utility
- Create a RAID 10 array
- Initialize and format the array
- Optional: Benchmark performance
Let’s go through each step in more detail:
1. Check RAID Controller and Determine RAID Utility
First, you need to identify your existing RAID controller and determine the utility to use for configuration:
- If hardware RAID, check vendor documentation for the configuration utility
- If software RAID, determine OS support and RAID management tools
Examples include Dell OpenManage, LSI MegaCLI, Intel RST, Windows Server Manager, Linux mdadm, etc. This is needed to access and manage the RAID setup.
2. Install Compatible Physical Drives
Install at least 4 new matching drives into your server or workstation that are compatible with your RAID controller. More drives can enhance performance.
Double check that the drives are intended for RAID configurations and not already part of another RAID array. Initialize or format the disks if needed.
3. Enter the RAID Configuration Utility
Boot into the configuration utility, usually during machine startup. For hardware RAID, this may involve hitting a certain key during POST to access the configuration menu.
For software RAID, you may need to access the boot menu and select the RAID management tool. Refer to your controller or software documentation for details.
4. Create the RAID 10 Array
Within the RAID configuration screen or wizard, select the option to create a new array. When prompted, choose RAID 10 or RAID 1+0.
Select the physical disks you want to include in the array. The minimum is 4 drives, but more can be added.
5. Initialize and Format the Array
After the RAID 10 array is created, the disks will show up as a single logical volume. Initialize the array and then format it with a file system like NTFS, ext4, XFS, etc.
You may need to reboot first before the array is visible to the operating system. Now it can be accessed as a single volume.
6. Optional: Benchmark Performance
Run disk benchmarks to validate performance improvements versus a single disk. RAID 10 can provide significant gains for read and write workloads.
Common benchmarking tools include CrystalDiskMark, ATTO Disk, IOmeter, and AS SSD Benchmark. Compare against benchmarks from a single disk.
RAID 10 Configuration Examples
Let’s look at some examples of configuring RAID 10 on various setups:
4 Drive Hardware RAID 10
1. Use Dell OpenManage to access PERC controller
2. Create new array and select RAID 10
3. Add 4 physical disks to array
4. Reboot and initialize RAID 10 volume
5. Format with NTFS and begin using volume
6 Drive Linux Software RAID 10
1. Enter mdadm utility at Linux command line
2. Create RAID 10 array with 6 disks, 2 spans of 3 mirrors each
3. Use commands like mdadm –create to initialize array
4. Format RAID device with XFS or other filesystem
5. Mount device and start using new RAID volume
8 Drive Windows Software RAID 10
1. Launch Server Manager and access Storage Pools
2. Create new pool and specify RAID 10
3. Select 8 compatible physical disks to add
4. Initialize and format the volume with NTFS
5. Allocate drive letter and begin saving data
These examples illustrate RAID 10 configuration across different hardware and software platforms. The overall process is similar.
Verifying and Monitoring RAID 10
Once configured, best practices include:
- Verifying RAID 10 information in management utility
- Running disk benchmarks to validate performance
- Monitoring disk health with SMART data
- Enabling monitoring and alerts on failed disks
This helps ensure RAID 10 is running optimally and identifies any potential disk issues.
Verifying RAID Status
The RAID management utility used to configure the array will also provide status information:
- Confirm RAID level is reporting as RAID 10
- Check the RAID state is reported as optimal
- Verify synchronized status and rebuild progress if applicable
- Confirm number of disks match expected configuration
This validates the RAID 10 array is properly created and functioning.
Monitoring Disk Health
Monitor individual disk health using utilities like:
- SMART data – monitors disk attributes like reallocated sectors, pending sectors, etc.
- SCSI Sense Codes – reports issues detected by the disk hardware itself
- RAID monitoring tools – check disk statistics and alerts
Watch for signs of deterioration and preemptively replace disks before they fail. This protects the RAID redundancy.
Rebuilding Failed Disks in RAID 10
In the event of a disk failure in RAID 10, a hot spare or replacement disk can be rebuilt into the array. The process involves:
- Physically replacing the failed drive with a compatible spare
- Marking the disk as a dedicated hot spare or assigning it to the array
- The RAID controller will automatically rebuild the drive, syncing the mirror
- Monitor rebuild progress until complete
The time to rebuild depends on the storage capacity and activity during the rebuild. Large drives or busy arrays may take hours.
When a disk fails, hot swap the failed drive as soon as possible to start rebuilds. Replace any other degraded disks that are reporting errors.
Expanding RAID 10 Storage
To expand the total capacity of your RAID 10 array:
- Determine current configuration and required disk count for expansion
- Add the needed number of disks (in pairs to mirror)
- Extend the existing array with the new disks
- The added storage capacity is now available as free space
Adding more disk pairs will grow the RAID 10 set. Make sure to use compatible disks of same size and type as existing array. Expanding may require downtime.
Migrating RAID 10 to New Disks
To migrate RAID 10 to new disks:
- Create a new RAID 10 array on the new disks, same total count
- Copy data from the old array to the new array
- Redirect applications to use the new array
- Decommission or repurpose old RAID 10 disks
Migration can be done disk-by-disk for large arrays to reduce downtime. Monitor progress until complete.
Use this process to upgrade disks or refresh existing arrays with minimal disruption. New disks can offer larger capacity, better performance, or updated technology.
Transitioning RAID 10 to RAID 6
To transition from RAID 10 to RAID 6:
- Audit RAID 10 array and determine minimum disk count for RAID 6
- Add additional drives to meet the minimum requirement
- Backup data from RAID 10 array as a precaution
- Create a RAID 6 array on the disks
- Migrate data from RAID 10 and verify
- Delete the old RAID 10 array
RAID 6 offers double parity allowing better fault tolerance than RAID 10 on larger arrays. For maximum redundancy, transition to RAID 6 once you exceed 8 total drives.
Best Practices for RAID 10
To maximize performance and reliability of RAID 10:
- Use disks designed and rated for RAID environments
- Select disks with similar specs – model, speed, capacity
- Limit arrays to 8 drives maximum, consider RAID 6 beyond
- Spread arrays across separate controllers if possible
- Leave 10-15% free space to avoid saturation
- Monitor disk health statistics regularly
- Keep firmware and drivers up-to-date
Properly architected RAID 10 provides a balance of speed, redundancy, and data protection for critical business workloads.
Conclusion
RAID 10 delivers optimized read and write performance plus fault tolerance through a combination of mirroring and striping data across drives. It requires at least 4 disks and provides protection against up to 2 drive failures.
Carefully selecting compatible hardware and following best practices for configuration allows you to take advantage of the benefits of RAID 10 for your storage environment. Monitor ongoing disk health and promptly rebuild any failed drives to ensure maximum uptime and data protection.
