tgtadm
tgtadm is a command-line utility used to administer and manage iSCSI targets for the TGT iSCSI target framework, which is commonly used to set up and control iSCSI storage devices in Linux environments. iSCSI (Internet Small Computer Systems Interface) is a protocol that allows SCSI commands to be sent over IP networks, enabling the use of remote storage devices as though they were locally attached.
The tgtadm tool interacts with the TGT daemon (tgtd) to manage iSCSI targets, including creating, modifying, and removing targets, logical units (LUNs), and access control lists (ACLs).
Key Concepts:
iSCSI Target: A storage resource located on a server that can be accessed over a network by an iSCSI initiator (the client).
LUN (Logical Unit Number): A logical reference to a portion of a storage device or a whole storage device.
TGT Daemon: The background process (
tgtd) that manages the targets and handles the iSCSI protocol.
Usage of tgtadm:
tgtadm:Here are common operations using tgtadm to manage iSCSI targets.
1. List existing targets:
This will list all the currently configured targets and their parameters.
2. Create a new target:
Example:
This creates a new target with the target ID (tid) of 1 and a unique iSCSI Qualified Name (IQN).
3. Bind the target to a network interface:
Example:
This binds the target to a specific network interface so that only clients from the specified IP can access it.
4. Add a LUN to a target:
Example:
This creates a new LUN (with ID 1) that points to the block device /dev/sdb1 for the target with ID 1.
5. Set access control (ACL):
Example:
This binds the iSCSI target to a specific initiator, identified by its IQN, ensuring that only this initiator can connect.
6. Delete a target:
Example:
This will remove the target with the specified ID (in this case, target 1).
7. Remove a LUN from a target:
Example:
This will delete the logical unit (LUN) with ID 1 from target 1.
8. Modify target settings (e.g., authentication):
Example:
This sets up authentication credentials for the iSCSI target, ensuring that clients need to authenticate using this username and password.
9. Show LUN information:
This shows the status and configuration of all logical units (LUNs) associated with a specific target.
Conclusion:
tgtadm is a powerful tool for managing iSCSI targets and logical units on Linux servers. It is essential for environments where centralized storage is required over an IP network, providing flexible control over iSCSI-based storage systems. With tgtadm, administrators can manage targets, allocate storage, set up access control, and configure various iSCSI parameters to ensure robust and efficient storage solutions.
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