iSCSI on Debian/Ubuntu - Quick Start Guide

sudo apt update
sudo apt install -y open-iscsi multipath-tools
sudo systemctl enable --now open-iscsi multipathd

Configure dedicated storage interfaces using Netplan (Ubuntu/Debian 11+):

sudo tee /etc/netplan/50-storage.yaml > /dev/null <<EOF
network:
  version: 2
  renderer: networkd
  ethernets:
    <INTERFACE_NAME_1>:
      addresses:
        - <HOST_IP_1>/<CIDR>
      mtu: 9000
      dhcp4: no
      dhcp6: no
    <INTERFACE_NAME_2>:
      addresses:
        - <HOST_IP_2>/<CIDR>
      mtu: 9000
      dhcp4: no
      dhcp6: no
EOF

sudo netplan apply
ip addr show

Allow all traffic on storage interfaces (recommended for dedicated storage networks):

# Using UFW
sudo ufw allow in on <INTERFACE_NAME_1>
sudo ufw allow in on <INTERFACE_NAME_2>

# View/generate initiator name
cat /etc/iscsi/initiatorname.iscsi

# Set automatic startup
sudo sed -i 's/^node.startup = manual/node.startup = automatic/' /etc/iscsi/iscsid.conf
sudo systemctl restart open-iscsi

Register this initiator IQN with your FlashArray.

# Create and bind first interface
sudo iscsiadm -m iface -I iface0 --op=new
sudo iscsiadm -m iface -I iface0 --op=update -n iface.net_ifacename -v <INTERFACE_NAME_1>

# Create and bind second interface
sudo iscsiadm -m iface -I iface1 --op=new
sudo iscsiadm -m iface -I iface1 --op=update -n iface.net_ifacename -v <INTERFACE_NAME_2>

# Discover targets
sudo iscsiadm -m discovery -t sendtargets -p <PORTAL_IP_1>:3260
sudo iscsiadm -m discovery -t sendtargets -p <PORTAL_IP_2>:3260

# Login via each interface to each portal
sudo iscsiadm -m node -T <TARGET_IQN> -p <PORTAL_IP_1>:3260 -I iface0 --login
sudo iscsiadm -m node -T <TARGET_IQN> -p <PORTAL_IP_2>:3260 -I iface0 --login
sudo iscsiadm -m node -T <TARGET_IQN> -p <PORTAL_IP_1>:3260 -I iface1 --login
sudo iscsiadm -m node -T <TARGET_IQN> -p <PORTAL_IP_2>:3260 -I iface1 --login

# Set automatic login
sudo iscsiadm -m node -T <TARGET_IQN> --op=update -n node.startup -v automatic

# Verify sessions
sudo iscsiadm -m session

Create /etc/multipath.conf:

sudo tee /etc/multipath.conf > /dev/null <<'EOF'
defaults {
    find_multipaths      no
    polling_interval     10
    path_selector        "service-time 0"
    path_grouping_policy group_by_prio
    failback             immediate
    no_path_retry        0
}

# Blacklist local devices and NVMe to prevent dm-multipath management
# NVMe uses native multipath (nvme_core multipath=Y), not dm-multipath
blacklist {
    # Local boot devices (adjust patterns for your environment)
    devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
    devnode "^sd[a]$"    # Adjust if boot device differs

    # All NVMe devices - use native NVMe multipath instead
    devnode "^nvme"

    # Virtual devices
    devnode "^vd[a-z]"
}

# Add device-specific settings for your storage array
# Default configurations for many storage arrays are included in the multipath package
# Example for a storage array supporting ALUA:
#devices {
#    device {
#        vendor           "VENDOR"
#        product          "PRODUCT"
#        path_selector    "service-time 0"
#        hardware_handler "1 alua"
#        path_grouping_policy group_by_prio
#        prio             alua
#        failback         immediate
#        path_checker     tur
#        fast_io_fail_tmo 10
#        dev_loss_tmo     60
#        no_path_retry    0
#    }
#}
EOF

# Restart multipathd to apply configuration
sudo systemctl restart multipathd

# Verify multipath devices (should only show iSCSI devices)
sudo multipath -ll

# Find multipath device
sudo multipath -ll
# Example: mpatha

# Create LVM
sudo pvcreate /dev/mapper/mpatha
sudo vgcreate iscsi-storage /dev/mapper/mpatha
sudo lvcreate -L 500G -n data iscsi-storage

# Format and mount (Debian/Ubuntu: ext4 recommended)
sudo mkfs.ext4 /dev/iscsi-storage/data
sudo mkdir -p /mnt/iscsi-storage
sudo mount /dev/iscsi-storage/data /mnt/iscsi-storage

# Add to fstab
echo '/dev/iscsi-storage/data /mnt/iscsi-storage ext4 defaults,_netdev 0 0' | sudo tee -a /etc/fstab

# Check sessions
sudo iscsiadm -m session

# Check multipath
sudo multipath -ll

# Verify storage
df -h | grep iscsi