Kernel Selection Strategy

Linux
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UEK vs RHCK Decision Matrix

Factor UEK (Recommended) RHCK
Performance 5-10% better storage I/O Standard performance
Latest Features Newer NVMe drivers Conservative updates
Ksplice Support Zero-downtime updates Not available
RHEL Compatibility Oracle-specific Binary compatible
Oracle Support Full support Full support
Stability Production-ready Very stable

UEK Version Recommendations

For NVMe-TCP workloads:

UEK R7 (5.15+): Recommended for Oracle Linux 8 and 9

  • Enhanced NVMe multipath

  • Better TCP performance

  • Improved NUMA awareness

  • Latest security fixes

UEK R6 (5.4): Minimum for production

  • Stable NVMe-TCP support

  • Good performance

  • Long-term support

Check and upgrade UEK:

# Check current UEK version
uname -r

# List available UEK versions
sudo dnf list available kernel-uek

# Install latest UEK
sudo dnf install -y kernel-uek

# Set as default
sudo grubby --set-default=/boot/vmlinuz-$(rpm -q --qf '%{VERSION}-%{RELEASE}.%{ARCH}\n' kernel-uek | tail -1)

# Reboot
sudo reboot

Kernel Boot Parameters for Storage

Recommended boot parameters for UEK:

# Edit GRUB configuration
sudo nano /etc/default/grub

# Add to GRUB_CMDLINE_LINUX:
# intel_iommu=on iommu=pt nvme_core.multipath=Y

# For NUMA systems, add:
# numa_balancing=disable

# Update GRUB
sudo grub2-mkconfig -o /boot/grub2/grub.cfg

# Reboot
sudo reboot

Why these parameters:

  • intel_iommu=on iommu=pt: Enables IOMMU passthrough for better performance

  • nvme_core.multipath=Y: Ensures NVMe native multipath is enabled (directly affects NVMe behavior)

  • numa_balancing=disable: Prevents automatic NUMA balancing which can hurt storage performance

Important:

The intel_iommu and numa_balancing parameters are general CPU and NUMA optimizations that improve overall system performance for I/O-intensive workloads. They do not directly affect NVMe-TCP protocol behavior. Measure baseline performance before and after changes to validate impact in your environment. Only nvme_core.multipath=Y directly affects NVMe multipath behavior.