No Connections Established Using NVMe-TCP or iSCSI on RHEL/Rocky/AlmaLinux

NVMe-TCP or iSCSI on RHEL/Rocky/AlmaLinux

• No devices appear after connection attempt
• nvme list or iscsiadm -m session shows no connections
• Multipath shows no devices

• Cables disconnected or bad
• Switches mis-configured
• VLAN mis-configured
• Mis-matching MTU settings
• Host or storage array firewall blocking required ports: NVMe-TCP (4420 data, 8009 discovery)
• Incorrect IP address configuration
• Incorrect NQN
• Host is not registered on FlashArray

Diagnosis:

# Check network connectivity
ping <storage_portal_ip>

# Check if storage port is reachable
nc -zv <storage_portal_ip> 4420  # NVMe-TCP
nc -zv <storage_portal_ip> 3260  # iSCSI

# Check firewall rules
iptables -L -n -v | grep <port>

# Check routing
ip route get <storage_portal_ip>

# Verify interface is up
ip link show <storage_interface>

Solutions:

1. Network connectivity issue:
   • Verify cable connections
   • Check switch configuration
   • Verify VLAN configuration
   • Check MTU settings match end-to-end
2. Firewall blocking:
   • Allow required ports: NVMe-TCP (4420 data, 8009 discovery), iSCSI (3260)
   • Check both host and storage array firewalls
   • Recommended: For dedicated storage networks, use trusted zone to disable filtering on storage interfaces (reduces CPU overhead)
3. Incorrect configuration:
   • Verify portal IP addresses
   • Check subsystem NQN or target IQN
   • Verify host identifier is registered on storage array