ISCSI is scsi (Small Computer System Interface) over IP. Where SCSI is the protocol and IP is the transport mechanism. This is going to be a quick and dirty overview of how to login to and mount an iscsi disk. This will not be an overview of how to share out a disk via iscsi. I may get around to writing that post, but it will not be today.
Before we get started we need to understand a few simple terms.
- ISCSI Initiator – the client that needs access to the ISCSI disk.
- ISCSI Target – the remote disk.
- ISCSI Target Portal – the server that is providing the Target to the Initiator
- IQN – The “ISCSI Qualified Name” or more simply a unique name for the Initiator and the Target
Now lets get down to business.
First on the Target you must install the ISCSI utils.
>yum -y install iscsi-initiator-utils.x86_64
Then discover the any ISCSI targets provided by the Target Portal. In this case the IP address of my target portal will be 192.168.0.55.
>iscsiadm -m discovery -t st -p 192.168.0.55.
In the example above -m puts iscsiadm is discovery mode, -t st tells iscsiadm to look for a SCSI target, and -p is the target portal. The output of the above command will be the IQN of the target disk.
For this example we will say that the IQN is
Then log into the ISCSI target
>iscsiadm -m node -T iqn.2001-05.com.equallogic:6-8a0900-5e1812101-1cf000245514a8da-disk1 -p 192.168.0.55 -l
In the example above we are setting the mode to node, -T prefaces the ISCSI target, -p the portal, and -l means login.
Now you need to identify which device is the iscsi target by looking at the output of dmesg or tail the messages file.