How to Configure iSCSI Initiator on AlmaLinux

Here’s a detailed blog post on configuring an iSCSI initiator on AlmaLinux. This step-by-step guide ensures you can seamlessly connect to an iSCSI target.

How to Configure iSCSI Initiator on AlmaLinux

The iSCSI (Internet Small Computer Systems Interface) protocol is a popular solution for accessing shared storage over a network, offering flexibility and scalability for modern IT environments. Configuring an iSCSI initiator on AlmaLinux allows your system to act as a client, accessing storage devices provided by an iSCSI target.

In this guide, we’ll walk through the steps to set up an iSCSI initiator on AlmaLinux, including prerequisites, configuration, and troubleshooting.

What is an iSCSI Initiator?

An iSCSI initiator is a client that connects to an iSCSI target (a shared storage device) over an IP network. By using iSCSI, initiators can treat remote storage as if it were locally attached, making it ideal for data-intensive environments like databases, virtualization, and backup solutions.

Step 1: Prerequisites

Before starting, ensure the following:

1. System Requirements:

   • AlmaLinux 8 or later.
   • Root or sudo access to the system.

2. Networking:

   • The iSCSI target server must be accessible via the network.
   • Firewall rules on both the initiator and target must allow iSCSI traffic (TCP port 3260).

3. iSCSI Target:

   • Ensure the target is already configured. Refer to our iSCSI Target Setup Guide for assistance.

Step 2: Install iSCSI Initiator Utilities

Install the required tools to configure the iSCSI initiator:

sudo dnf install iscsi-initiator-utils -y

Verify the installation:

iscsiadm --version

The command should return the installed version of the iSCSI utilities.

Step 3: Configure the Initiator Name

Each iSCSI initiator must have a unique IQN (iSCSI Qualified Name). By default, AlmaLinux generates an IQN during installation. You can verify or edit it in the configuration file:

sudo nano /etc/iscsi/initiatorname.iscsi

The file should look like this:

InitiatorName=iqn.2024-12.com.example:initiator1

Modify the InitiatorName as needed, ensuring it is unique and matches the format iqn.YYYY-MM.domain:identifier.

Save and close the file.

Step 4: Discover Available iSCSI Targets

Discover the targets available on the iSCSI server. Replace <target_server_ip> with the IP address of the iSCSI target server:

sudo iscsiadm -m discovery -t sendtargets -p <target_server_ip>

The output will list available targets, for example:

192.168.1.100:3260,1 iqn.2024-12.com.example:target1

Step 5: Log In to the iSCSI Target

To connect to the discovered target, use the following command:

sudo iscsiadm -m node -T iqn.2024-12.com.example:target1 -p 192.168.1.100 --login

Replace:

• iqn.2024-12.com.example:target1 with the target’s IQN.
• 192.168.1.100 with the target server’s IP.

Once logged in, the system maps the remote storage to a local block device (e.g., /dev/sdX).

Step 6: Verify the Connection

Confirm that the connection was successful:

1. Check Active Sessions:

   sudo iscsiadm -m session
   

   The output should list the active session.

2. List Attached Devices:

   lsblk
   

   Look for a new device, such as /dev/sdb or /dev/sdc.

Step 7: Configure Persistent Connections

By default, iSCSI connections are not persistent across reboots. To make them persistent:

1. Enable the iSCSI service:

   sudo systemctl enable iscsid
   sudo systemctl start iscsid
   

2. Update the iSCSI node configuration:

   sudo iscsiadm -m node -T iqn.2024-12.com.example:target1 -p 192.168.1.100 --op update -n node.startup -v automatic
   

Step 8: Format and Mount the iSCSI Device

Once connected, the iSCSI device behaves like a locally attached disk. To use it:

1. Format the Device:

   sudo mkfs.ext4 /dev/sdX
   

   Replace /dev/sdX with the appropriate device name.

2. Create a Mount Point:

   sudo mkdir /mnt/iscsi
   

3. Mount the Device:

   sudo mount /dev/sdX /mnt/iscsi
   

4. Verify the Mount:

   df -h
   

   The iSCSI device should appear in the output.

Step 9: Add the Mount to Fstab

To ensure the iSCSI device is mounted automatically on reboot, add an entry to /etc/fstab:

/dev/sdX /mnt/iscsi ext4 _netdev 0 0

The _netdev option ensures the filesystem is mounted only after the network is available.

Troubleshooting Common Issues

1. Issue: Cannot Discover Targets

   • Ensure the target server is reachable:

     ping <target_server_ip>
     

   • Check the firewall on both the initiator and target:

     sudo firewall-cmd --add-port=3260/tcp --permanent
     sudo firewall-cmd --reload
     

2. Issue: iSCSI Device Not Appearing

   • Check for errors in the system logs:

     sudo journalctl -xe
     

3. Issue: Connection Lost After Reboot

   • Ensure the iscsid service is enabled and running:

     sudo systemctl enable iscsid
     sudo systemctl start iscsid
     

Conclusion

Configuring an iSCSI initiator on AlmaLinux is an essential skill for managing centralized storage in enterprise environments. By following this guide, you can connect your AlmaLinux system to an iSCSI target, format and mount the storage, and ensure persistent connections across reboots.

With iSCSI, you can unlock the potential of network-based storage for applications requiring flexibility, scalability, and reliability.