## The AIX ghostdev parameter 

You use the AIX ghostdev  parameter mainly for taking an image of an AIX operating system by using something like the AIX mksysb facility, and then you use that mksysb image to build more AIX VMs. AIX uses the ghostdev  parameter to: 

GLYPH<SM590000> Determine whether it is operating on the same hardware as previously. 

GLYPH<SM590000> If it is a new AIX image, it clears the host name and IP address configuration. 

GLYPH<SM590000> It also clears the VG information and disk drive information, and sets devices to their default settings. 

Without the ghostdev  parameter, a copied AIX VM comes up with the previous host name, IP address, and device configuration. Because those devices no longer exist on the copied VM, they are in Defined  state. We call these devices ghost  devices, hence the name of the ghostdev  parameter. 

You use the ghostdev  setting because you want to prevent the primary site IP addresses from becoming active, even for a short period, at the DR site. However, the clearing of the VG information and setting of devices to their default values means that you must use scripts to return those values to their customize settings. 

## Gathering environment configuration data 

The first step in this process is to gather data that is pertinent for the configuration of the VM at each site. For each site, you need: 

GLYPH<SM590000> The machine type and the serial number of the system (host) the VM moves from and to. 

GLYPH<SM590000> The host name of the VM when it is at each host. 

GLYPH<SM590000> The related network configuration of the VM when it is at each host: 

– IP address 

–N e t m a s k 

– Default gateway 

– DNS server 

The machine type and serial number of the host is obtained by running the AIX prtconf command. The network parameters (for example, IP address, and so on) can probably be acquired from your network administrator. 

Example 1-1 shows an example of using prtconf  from the AIX VM to gather system model and serial number information. 

root@rt11006: / # prtconf | grep -iE "system model|serial number" System Model: IBM,8286-42A Machine Serial Number: 2100E5W 

