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Connect a Linux iSCSI Initiator and Mount a LUN

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Discover the target, configure CHAP, log in, identify the new disk, and make both the session and filesystem survive a restart.

LinuxOpen-iSCSIiscsiadmStorage
Linux iSCSI initiator workflow from discovery and CHAP login to detecting and mounting a LUN
5-part learning path

iSCSI Storage Learning Path

Move from the block-storage model to target setup, Linux and Windows initiators, then production troubleshooting and MPIO.

Part 3 of 5
Lesson overview

In This Lesson

Connect a Linux host to an authorized iSCSI LUN without confusing discovery, login, and filesystem work. You will verify the session and disk at every stage before enabling persistence.

  1. What this guide assumes
  2. Workflow
  3. Install and start the initiator
  4. Verify the initiator IQN and discover the target
  5. Configure CHAP and log in
  6. Verify the session and identify the new disk
  7. Partition, format and mount the new LUN
  8. Configure automatic login and mounting
From concept to practice

Workflow: Discover and authenticate → Make it persistent

Keep this three-step view in mind as you work through the detailed lesson.

1

Discover and authenticate

Confirm the initiator IQN, find the target, configure CHAP, and log in.

2

Prepare the device

Identify the new disk carefully, then partition, format, and mount it.

3

Make it persistent

Configure startup login and mounting with stable identifiers, then test a reboot-safe path.

Fast orientation

Connect a Linux iSCSI Initiator and Mount a LUN Overview

Use this summary to establish the big picture before moving into the detailed explanations, commands, and checks.

Core focus

Connect a Linux host to an authorized iSCSI LUN without confusing discovery, login, and filesystem work.

Key connection

Discover and authenticate → Prepare the device → Make it persistent

Practical outcome

You will verify the session and disk at every stage before enabling persistence.

What this guide assumes

The target is already listening at 192.168.50.10:3260, exports iqn.2026-08.in.netest:storage.target01, and has an ACL matching this Linux client's initiator IQN.

Disk safety: commands below use /dev/sdb only as an example. Confirm the newly attached device by size, model and session mapping before partitioning or formatting it.

Workflow

  1. Install and start Open-iSCSI
  2. Verify the IQN and discover the target
  3. Configure CHAP and log in
  4. Verify the session and disk
  5. Partition, format and mount
  6. Make the connection persistent
  7. Test and disconnect safely

1. Install and start the initiator

RHEL, Rocky Linux or AlmaLinux

dnf install iscsi-initiator-utils -y systemctl enable --now iscsid systemctl enable iscsi

Ubuntu or Debian

apt update apt install open-iscsi -y systemctl enable --now iscsid

The main files are /etc/iscsi/iscsid.conf and /etc/iscsi/initiatorname.iscsi.

2. Verify the initiator IQN and discover the target

cat /etc/iscsi/initiatorname.iscsi

The displayed IQN must match the target ACL. If you intentionally change it, restart iscsid and update the target ACL.

iscsiadm -m discovery -t sendtargets -p 192.168.50.10

Expected discovery output:

192.168.50.10:3260,1 iqn.2026-08.in.netest:storage.target01

Discovery records the target but does not attach its LUN yet.

3. Configure CHAP and log in

Set authentication on this target node rather than placing one global password in iscsid.conf.

iscsiadm -m node \ -T iqn.2026-08.in.netest:storage.target01 \ -p 192.168.50.10:3260 \ --op update -n node.session.auth.authmethod -v CHAP iscsiadm -m node \ -T iqn.2026-08.in.netest:storage.target01 \ -p 192.168.50.10:3260 \ --op update -n node.session.auth.username -v iscsiuser iscsiadm -m node \ -T iqn.2026-08.in.netest:storage.target01 \ -p 192.168.50.10:3260 \ --op update -n node.session.auth.password -v 'Use-A-Strong-Secret'

Log in:

iscsiadm -m node \ -T iqn.2026-08.in.netest:storage.target01 \ -p 192.168.50.10:3260 --login

4. Verify the session and identify the new disk

iscsiadm -m session iscsiadm -m session -P 3 lsblk -o NAME,SIZE,TYPE,FSTYPE,MOUNTPOINTS,MODEL dmesg | tail -50

The detailed session output links the target and its attached SCSI device. Compare lsblk before and after login, and confirm the expected size.

Do not assume the disk is always /dev/sdb. Kernel device names can change after hardware changes or restart.

5. Partition, format and mount the new LUN

Create one GPT partition

parted /dev/sdb --script mklabel gpt parted /dev/sdb --script mkpart primary 0% 100% partprobe /dev/sdb lsblk /dev/sdb

Create a filesystem once

mkfs.xfs /dev/sdb1 # Or, choose ext4 instead: mkfs.ext4 /dev/sdb1

Mount it

mkdir -p /mnt/iscsi-data mount /dev/sdb1 /mnt/iscsi-data df -hT /mnt/iscsi-data
Formatting destroys the previous filesystem. Never rerun mkfs on an existing LUN that contains data.

6. Configure automatic login and mounting

iscsiadm -m node \ -T iqn.2026-08.in.netest:storage.target01 \ -p 192.168.50.10:3260 \ --op update -n node.startup -v automatic blkid /dev/sdb1

Add the real filesystem UUID to /etc/fstab. For XFS:

UUID=2a8e16d2-3dbc-4e63-bdc5-331e01234567 /mnt/iscsi-data xfs _netdev,nofail 0 0

_netdev tells the system that the mount depends on network storage. Test the entry before rebooting:

umount /mnt/iscsi-data mount -a findmnt /mnt/iscsi-data

7. Test the storage and disconnect safely

echo "iSCSI storage test" > /mnt/iscsi-data/test.txt cat /mnt/iscsi-data/test.txt sync findmnt /mnt/iscsi-data iscsiadm -m session -P 1

When removing the LUN, stop applications, unmount the filesystem, then log out:

fuser -vm /mnt/iscsi-data umount /mnt/iscsi-data iscsiadm -m node \ -T iqn.2026-08.in.netest:storage.target01 \ -p 192.168.50.10:3260 --logout

If the node will never be used again, delete its saved record only after a clean logout:

iscsiadm -m node \ -T iqn.2026-08.in.netest:storage.target01 \ -p 192.168.50.10:3260 -o delete

Connect a Linux iSCSI Initiator and Mount a LUN Frequently Asked Questions

How do I discover an iSCSI target in Linux?

Run iscsiadm -m discovery -t sendtargets -p TARGET_IP. Confirm that TCP 3260 is reachable first.

How do I make the connection persistent?

Set node.startup to automatic, enable the initiator services, mount by filesystem UUID and include _netdev.

Why is the disk not showing after login?

Inspect iscsiadm -m session -P 3, lsblk and kernel messages. The target must map a LUN to the ACL for this exact initiator IQN.

Why mount by UUID?

Device names such as /dev/sdb can change. A filesystem UUID identifies the intended filesystem more reliably.

Reference

See Red Hat's Configuring an iSCSI initiator documentation for current service, discovery and persistent-mount guidance.