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## 2.1.4 Configuring with two IBM LinuxONE servers 

This scenario extends the previous single configuration with the possibility of greater availability and disaster recovery. This two-server configuration can range from a simple cold standby to an active/active configuration. As a foundation, duplicate the components and locate them (at a minimum) in two different computing rooms, or (for maximum protection) at two different site locations. For clarity and use purposes, name one site as primary  and the other site as DR . This naming purpose is especially important to the disk storage subsystem for your failover procedures. This naming can be diminished to each stage. You can verify usability by reverting the primary and DR sites during a testing stage. With the two-server configuration, you are able to spread all the I/Os over all the disk storage boxes and use the cache of each box. 

## Path length considerations 

Calculate the length of the path between the IBM LinuxONE server and the storage subsystem and between the two storage subsystems. The length influences the round-trip time. Round-trip time is the amount of time between when a request is sent out and the corresponding answer is received. This includes the following events: 

GLYPH<SM590000> The signal travels on the wire to the receiver 

GLYPH<SM590000> The receiver gets the request, processes it and sends an answer 

GLYPH<SM590000> The answer travels on the wire back to the requester 

The shorter the round-trip time, the faster the process. 

## LPAR considerations 

Ensure that the LPARS are spread across the machines, run more than one instance of each service and distribute them over the defined LPARs. This two-server configuration with these basics provides redundancy for both planned and unplanned outages in hardware and software. Figure 2-2 on page 20 shows a two-site configuration. 

<img src='content_image/986064.jpg'>

## 2.1.5 Configuring with three or more IBM LinuxONE servers 

In addition to a two-machine scenario, a configuration with three or more IBM LinuxONE servers enables some quorum (automated decision making) in your environment. As in the 

