Setting Up and Verifying RAID 0 on MegaRAID Controllers

RAID0 (striping) on enterprise RAID controllers like Broadcom MegaRAID is used to expose multiple disks as a single logical volume with no redundancy. This configuration is appropriate only for performance-critical workloads where data loss from a single disk failure is acceptable, or for temporary/cache storage. This guide covers the full setup process on servers with MegaRAID controllers.

Prerequisites

• Physical or IPMI/console access to the server BIOS
• New disk(s) physically installed and detected by the controller
• Clear understanding that RAID0 offers zero fault tolerance — any single disk failure destroys all data on the array
• Controller firmware up to date (check Broadcom’s support site for your specific model)

Step 1: Initialize Disks to Unconfigured Good Status

New disks arrive in an unconfigured state and must be initialized before RAID configuration.

Via MegaRAID BIOS Interface:

1. Reboot and enter the MegaRAID controller BIOS (typically Ctrl+H during POST; check your server’s boot messages)
2. Navigate to Physical View or Disk Groups → Physical Disks
3. Select the new disk and press Enter
4. Choose Make Unconf Good or Initialize Disk
5. Confirm the operation

The disk status should now display as “Unconf Good” or “Online (Unconfigured)”. Verify disk details—capacity, model, firmware version—in this view. Some newer firmware versions auto-initialize new disks; consult your controller’s release notes if disks appear ready without manual intervention.

Step 2: Create the RAID0 Array

Once disks show “Unconf Good” status, configure them into a RAID group.

Via MegaRAID Configuration Wizard:

1. From the Home screen, select Configuration Wizard or Add Configuration
2. Choose Manual Configuration (avoid Auto Configure to maintain control over stripe settings)
3. Select disk(s) from the left panel and click Add to Array
4. Selected disks appear as a new group on the right
5. Click Accept DG to proceed
6. Select Add to SPAN and confirm the stripe block size:
   • 64KB: default, suited for random I/O workloads
   • 256KB or larger: better for sequential I/O (databases, video streaming)
7. Click Next and verify the RAID level shows RAID0
8. Configure read/write cache settings based on your workload:
   • Write-Through: safest, no data loss on power failure but slower writes
   • Write-Back: faster writes, requires capacitor-backed cache or battery backup
9. Review the final summary showing all disk assignments and click Accept
10. Confirm initialization — the controller writes RAID metadata to all disks

The array initializes in the background. Monitor progress from the Home screen. Initialization time varies with disk size, typically 10-30 minutes. Performance may be reduced during initialization if the init rate is set aggressively.

Step 3: Verify Configuration in Linux

Reboot into Linux and verify the RAID0 array is recognized by the OS.

Check for the new logical drive:

lsblk
sudo fdisk -l

For Broadcom MegaRAID (newer controllers) using perccli:

sudo perccli /c0 show
sudo perccli /c0/v0 show
sudo perccli /c0/v0 /all show

For older LSI MegaRAID controllers using MegaCLI:

# Install MegaCLI if not present
sudo apt install megacli    # Debian/Ubuntu
sudo dnf install megacli    # RHEL/Fedora

# Display logical drive info
sudo megacli -LDInfo -Lall -a0

# Display physical disk info
sudo megacli -PDList -a0

# Check controller status
sudo megacli -AdpAllInfo -a0

The logical drive should appear as /dev/sdX or /dev/nvmeX depending on your controller type. Partition and format as needed for your application.

Important Considerations

Data Loss Risk

RAID0 provides zero redundancy. Use only for:

• Temporary or scratch storage
• Non-critical cache directories
• High-performance cache tiers with external redundancy
• Development/testing environments
• Performance-critical applications (HPC, real-time analytics) where availability is managed at a higher layer

Never use RAID0 for primary application storage, databases, or any data you cannot afford to lose.

Performance Tuning

Stripe Block Size: Start with 64KB for mixed workloads. Monitor I/O patterns and adjust if needed:

• Reduce for random I/O-heavy workloads (databases, general-purpose)
• Increase to 256KB+ for sequential workloads (streaming, backups)

Read/Write Cache:

• Enable Write-Back only if your controller has capacitor-backed cache (CBC) or a battery backup unit (BBU)
• Use Write-Through in virtual environments or if power loss risk is high
• Enable Read-Ahead for sequential workloads

Initialization Rate: Balance init speed against production workload impact:

• Fast init (100%) reduces time but impacts performance
• Slow init (10-30%) spreads load but extends completion time

Ongoing Monitoring

Check array health regularly:

sudo megacli -LDInfo -Lall -a0 | grep State
sudo megacli -PDList -a0 | grep "Firmware state"

Watch for:

• Offline or Failed physical disks — immediate data loss in RAID0
• Predictive Failures — replace disks before failure
• High temperature warnings — verify cooling

Set up alerting through your monitoring system (Prometheus, Nagios, etc.) to notify on disk state changes.

Remote Management

For hands-off deployments, configure RAID through IPMI or Redfish:

ipmitool -I lanplus -H <bmc_ip> -U <user> -P <pass> chassis power status

Consult your specific controller and server documentation for remote RAID configuration APIs.

Troubleshooting

Disks not detected:

• Verify disks are fully seated in the controller’s backplane
• Check BIOS for drive enumeration
• Update controller firmware to latest version

RAID0 creation fails:

• Ensure all disks have identical or compatible firmware versions
• Verify disks are not already assigned to another array
• Check for disk capacity mismatches (larger disks can be used, but wasteful)

Performance lower than expected:

• Check stripe block size matches your workload
• Verify cache is properly configured (CBC installed and functioning)
• Monitor for concurrent initialization or background tasks
• Check for host-side I/O bottlenecks (network, CPU, memory)