Adding hosts to the KSYS

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The KSYS monitors and manages the disaster recovery operations across sites. The KSYS requires that each host must be paired to another host across sites. This type of pairing allows the virtual machines to move from one host to another host across sites. You must plan the host pairing across sites in advance, and then implement the pairing.

Note: The VM Recovery Manager DR solution supports POWER7 processor-based server, or later.

Host pairing guidelines

Each host in a pair must belong to different sites.
Paired host in the backup site must always have enough resources to host the managed virtual machines from the active site. For example, if the current active site is Site_1 and the Host_1 host in that site is running 55 virtual machines that requires 100 cores CPU and 512 GB memory, you can pair the Host_1 host from the active site with the Host_2 host on the backup site only when the Host_2 host contains at least 100 cores CPU and 512 GB memory. If the capacity is not sufficient in the backup host, the validation issues warnings.
If you use the Enterprise Pool capacity option, the Host_2 host can borrow required resources from the Enterprise Pool before the disaster recovery movement.
You can pair the POWER8 host and the POWER7 hosts. For example, you can pair a POWER8 host on the active site with a POWER7 host on the backup site if the POWER7 system has enough resources to host the virtual machines from the POWER8 host. Same is applicable vice-versa.

After the HMCs are added to the KSYS, you can review the list of managed hosts by each HMC, and then identify the hosts that you want to add to the KSYS for disaster recovery. You must connect the source hosts and target hosts to different HMCs across sites. If you connect the source hosts and target hosts to the same HMC, it leads to an invalid configuration in the KSYS subsystem and can cause failures in disaster recovery operations.

When a host is added to a host group, all the virtual machines in the host are included by default in the disaster recovery management scope. However, the disaster recovery management starts only after you configure the subsystems and run the discovery and verification operations. Therefore, if you plan to exclude a set of virtual machines after adding the hosts, you can unmanage those virtual machines, and then run the discovery and verification operations.

You can prioritize the virtual machines within a single host or among multiple hosts such that the virtual machines that run important workloads are considered first for the move operation. You can set a priority of high, medium, or low for the virtual machines. When you run a move operation, the ksysmgr command initiates the operation for the virtual machines that has the highest priority.

Tip: Obtain the host name by querying the HMC. You can copy the host name and use it when you run commands.

To add the hosts to the KSYS configuration, complete the following steps in the KSYS LPAR:

Add the managed host (for example, host name: Site1_host1), which is running the workload, to the KSYS by running the following command:
```
ksysmgr add host Site1_host1 site=Site1
```
The Site1_host1 host, which is a managed host for the Site1_HMC1 HMC, is added in the active site.
Add the backup host (for example, host name: Site2_host1), which acts as a backup host, to the KSYS by running the following command:
```
ksysmgr add host Site2_host1 site=Site2
```
The Site2_host1 host, which is a managed host for the Site2_HMC1 HMC, is added in the backup site.
Repeat Step 1 and Step 2 for all hosts that you want to add to the KSYS.

Optional: Verify the hosts that you added by running the following command:

ksysmgr query host

An output that is similar to the following example is displayed:

                Name:            Site2_host1
                UUID:            c15e9b0c-c822-398a-b0a1-6180872c8518
                FspIp:
                Host_group:      No host_group defined
                Pair:            None
                Vswitchmap:      Not currently set
                Vlanmap:         Not currently set
                DrVswitchmap:    Not currently set
                DrVlanmap:       Not currently set
                Skip_power_on:   No
                Site:            Site2
                VIOS:            Site2_VIOS1
                Site2_VIOS2
                HMCs:            Site2_HMC1
                MachineSerial:   xyz

                Name:            Site1_host1
                UUID:            67ff62ec-ecb5-3ad4-9b35-0a2c75bb7fe4
                FspIp:
                Host_group:      No host_group defined
                Pair:            None
                Vswitchmap:      Not currently set
                Vlanmap:         Not currently set
                DrVswitchmap:    Not currently set
                DrVlanmap:       Not currently set
                Skip_power_on:   No
                Site:            Site1
                VIOS:            Site1_VIOS1
                Site1_VIOS2
                HMCs:            Site1_HMC1
                MachineSerial:   xyz

If you want to exclude some virtual machines during a recovery operation, run the following command for each virtual machine that you want to exclude:
```
ksysmgr unmanage vm name=vmname host=hostname | uuid=lparuuid | 
                    ALL host=hostname | ALL host_group=hg_name
```
Note: You can perform the unmanage operation only after creating the host pairs. For more information about host pairs, see the Creating host pairs topic.
You can include the VM back in the KSYS management at any time by using the ksysmgr manage vm vmname|lparuuid command.
If you want to specify a priority for specific virtual machines for the move operation, run the following command:
```
ksysmgr modify VM name1[,name2,name3,...] | file=filepath
   [uuid=uuid_value]
   [host=hostname]
   [priority=low|medium|high]
```
where, the file parameter is an XML file that contains a list of virtual machine references.