7.6.3 Unlimited hardware

Of course, not everyone has unlimited hardware. Many customers resist the prospect of purchasing extra hardware for the purposes of disaster recovery, let alone buying another identical copy of their production environment for upgrading purposes.

Fortunately, with System p and logical partitioning, it is very possible to carry out this process using your existing hardware and logical partitioning. The following high level steps should be used as a guide to carrying out an appserver upgrade, making it relevant to your particular environment. Similar steps could be used for operating system upgrades and even major application upgrades.

For our example, we use a very simple environment (although this sequence is possible even for complex environments), as shown in Figure 7-7.

Figure 7-7 A simple production environment which needs upgrading

Consider the following procedure:

1. Create an identical copy of the production environment; see Figure 7-8.

Figure 7-8 Create a new copy of the production environment

2. At a convenient time, when the system is least used, configure the load balancer to route new requests to the new systems; see Figure 7-9.

Figure 7-9 Configure new requests to be routed to the new environment

3. After all requests to the old environment have completed, the new environment will be serving all requests and the old environment will be available for rollback as needed; see Figure 7-10.

Figure 7-10 The new environment is serving all requests

4. After a suitable period of time has elapsed, the LPARs for the old environment can be archived and taken offline; see Figure 7-11.

Figure 7-11 The new environment is live