The nodes of the HP XC system exist in various states, which are described in Table 2-1.
A node's state depends on several factors, including the following:
Does the node need to be imaged?
The software on client nodes must be synchronized with a central collection of software for the nodes, called the golden image, which resides on a node called the golden client. Imaging replicates the software from the golden client onto the node using the rsync or flamethrower utilities. The golden image and software distribution are discussed in Chapter 8: Distributing Software Throughout the System.
Did the node fail to image?
Did the node fail to boot?
Table 2-1 Node States
| Node State | Description |
| Raw_Off | The node requires imaging and is powered off. Turning on the node's power initiates the imaging process. |
| Raw_On | The node requires imaging and is powered on. The node must be powered off to prepare for imaging. |
| POST | The node is powered on and should have entered BIOS self-test. The node can be imaged or booted. |
| Imaging | The node is in the process of imaging. After a successful imaging, the node is placed in the Boot_Ready state. If the node does not successfully image, the node is placed in the Image_Fail state. |
| Image_Fail | The imaging operation failed. The node is returned to the Raw_Off state. |
| Boot_Ready | The node is imaged, but currently powered off. The node is ready to boot. When the node is powered on, it is placed in the POST state. |
| Booting | The node is booting. If the node is successfully booted, the node will be placed in the AVAILABLE state. If the node does not successfully boot, the node is placed in the Boot_Fail state. |
| Boot_Fail | The node failed to boot. The node is returned to the Boot_Ready state. |
| AVAILABLE | The node is ready for use. |
Nodes transition between node states accordingly. Figure 2-1 illustrates the transition of node states.
A node that does not require imaging is powered on in the POST state, enters the Booting state when it is booting, and is in the Available state when it is ready for use in the HP XC system.
A node that requires imaging is considered to be in the Raw_Off state until it is powered on. Then it enters the POST state. When the node is imaged, it is in the Imaging state. After completing imaging, the node enters the Boot_Ready state and is returned to the POST state. When the node is booting, the node is in the Booting state. It enters the AVAILABLE state when it is ready for use.
A node that fails to image is returned to the Raw_Off node from the Image_Fail state.
A node that fails to boot is placed in the Boot_Fail state. Depending on the number of retries, it is placed in the Boot_Ready state and returns to the POST state to attempt booting again.
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