Troubleshooting

Multipath State Diagram

Quick Reference Table

Common Troubleshooting (iSCSI)

Connection Issues

Performance Issues

Multipath Issues

Storage Errors

Quick Reference

Common Commands

lsblk                           # List block devices
lsscsi                          # List SCSI devices
iscsiadm -m session             # List iSCSI sessions
iscsiadm -m session -P 3        # Detailed session info
multipath -ll                   # List multipath devices
multipathd show paths           # Show all paths
iostat -xz 1                    # I/O statistics
dmesg | grep -i iscsi           # Check for errors

Service Management

systemctl status iscsid         # Check iSCSI initiator
systemctl restart iscsid        # Restart iSCSI
systemctl status multipathd     # Check multipath daemon
multipathd reconfigure          # Reload multipath config

RHEL-Specific Troubleshooting

Check Service Status:

# Check all iSCSI-related services
sudo systemctl status iscsid
sudo systemctl status iscsi
sudo systemctl status multipathd

# Check for failed services
sudo systemctl --failed | grep -E "iscsi|multipath"

# View detailed service logs
sudo journalctl -xe -u iscsid

Network Troubleshooting:

# Check interface status
nmcli device status

# Check connection status
nmcli connection show

# Test connectivity to storage
ping -c 4 <portal_ip>

# Test iSCSI port
nc -zv <portal_ip> 3260

# Check routing
ip route get <portal_ip>

# Verify MTU
ip link show ens1f0 | grep mtu

Multipath Troubleshooting:

# Verbose multipath output
sudo multipath -v3

# Reload multipath configuration
sudo systemctl reload multipathd

# Reconfigure all devices
sudo multipath -r

# Check for blacklisted devices
sudo multipath -v3 | grep -i blacklist

# View device mapper tables
sudo dmsetup table
sudo dmsetup status

SELinux Troubleshooting:

# Check for recent denials
sudo ausearch -m avc -ts recent | grep iscsi

# Generate policy from denials
sudo ausearch -m avc -ts recent | audit2allow -M iscsi_troubleshoot

# Review generated policy
cat iscsi_troubleshoot.te

# Install if appropriate
sudo semodule -i iscsi_troubleshoot.pp

Performance Troubleshooting:

# Check I/O statistics
iostat -x 1 5

# Check for I/O wait
vmstat 1 5

# Check network performance
sar -n DEV 1 5

# Check for dropped packets
netstat -i

# Check IRQ distribution
cat /proc/interrupts | grep -E "eth|ens"

# Verify tuned profile
sudo tuned-adm active
sudo tuned-adm verify