Centralized Secure Storage (iSCSI) - \"Initiator Client\" Setup on CentOS

Centralized secure storage is an essential component of many modern IT infrastructures. It allows multiple servers to access a shared storage pool, enabling higher flexibility, scalability, and availability. One popular method is iSCSI (Internet Small Computer System Interface), which enables servers to access remote storage over IP networks as if it were locally attached.

What is iSCSI?

iSCSI is a protocol that encapsulates SCSI commands and data into IP packets, allowing servers to communicate with remote storage devices over standard Ethernet networks. This creates a Storage Area Network (SAN) using existing network infrastructure, making it cost-effective compared to dedicated Fibre Channel solutions.

iSCSI Components

Setting up iSCSI Initiator on CentOS

Step 1: Install Required Packages

Install the iSCSI initiator utilities using the package manager ?

sudo yum install iscsi-initiator-utils

For CentOS 8+ systems using dnf ?

sudo dnf install iscsi-initiator-utils

Step 2: Configure Initiator Name

Edit the initiator configuration to set a unique IQN ?

sudo vi /etc/iscsi/initiatorname.iscsi

Set the initiator name (example) ?

InitiatorName=iqn.2023-01.com.example:client01

Step 3: Start iSCSI Service

Enable and start the iSCSI services ?

sudo systemctl enable iscsid
sudo systemctl start iscsid
sudo systemctl enable iscsi
sudo systemctl start iscsi

Step 4: Discover iSCSI Targets

Scan the network for available iSCSI targets ?

sudo iscsiadm -m discovery -t st -p 192.168.1.100:3260

Replace 192.168.1.100 with your target's IP address. This returns discovered targets ?

192.168.1.100:3260,1 iqn.2023-01.com.example:storage.target01

Step 5: Login to iSCSI Target

Establish connection to the discovered target ?

sudo iscsiadm -m node -T iqn.2023-01.com.example:storage.target01 -p 192.168.1.100:3260 -l

Successful login creates a block device (e.g., /dev/sdb).

Step 6: Verify iSCSI Session

Check active iSCSI sessions ?

sudo iscsiadm -m session -P3

List available block devices ?

lsblk

Step 7: Format and Mount Storage

Create a filesystem on the new device ?

sudo mkfs.ext4 /dev/sdb

Create mount point and mount the device ?

sudo mkdir /mnt/iscsi-storage
sudo mount /dev/sdb /mnt/iscsi-storage

Step 8: Configure Automatic Mount

Add entry to /etc/fstab for persistent mounting ?

echo "/dev/sdb /mnt/iscsi-storage ext4 _netdev 0 0" | sudo tee -a /etc/fstab

The _netdev option ensures the mount waits for network availability.

Key Management Commands

Conclusion

Setting up an iSCSI initiator on CentOS provides cost-effective centralized storage access over IP networks. The configuration involves installing utilities, discovering targets, and establishing persistent connections. This solution scales storage infrastructure without requiring expensive dedicated hardware, making it ideal for virtualized environments and enterprise storage consolidation.