Now that we have a secure and reliable way to transfer files between computers (the subject of Chapter 4), we can make a backup copy, or system image, of one computer and store it on the disk drive of another computer. This system image can then be used to recover a system in the event of a disk crash, or it can be used to make a clone of the original system. Cloned systems can become backup servers in high-availability server pairs, or they can become cluster nodes. When changes are made to the original system, the cloned systems can be easily updated using a newly created system image of the original system.
Using the SystemImager package, we can turn one of the cluster nodes into a Golden Client that will become the master image used to build all of the other cluster nodes. We can then store the system image of the Golden Client on the backup server (offering the SSH server service discussed in the previous chapter). In this chapter, the backup server is called the SystemImager server, and it must have a disk drive large enough to hold a complete copy of the contents of the disk drive of the Golden Client, as shown in Figure 5-1.
Figure 5-1: The SystemImager server and Golden Client
Clones 1, 2, and 3 in this diagram are all exact copies of the Golden Client— only their IP address information and host names are different.
Here, then, are the steps for cloning a system using the SystemImager package.
Note | The following recipe and the software included on the CD-ROM do not contain support for SystemImager over SSH. To use SystemImager over SSH (on RPM-based systems) you must download and compile the SystemImager source code as described at http://www.systemimager.org/download. |