Creating asymmetric host group

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The VM Recovery Manager DR solution manages an environment in which M number of hosts on the home site are configured to failover with N number of hosts on the backup site. This is one-to-many pairing.

While creating host group, you can provide custom name of the composite group that is to be created.

For EMC storage agent, the composite group name of the source storage agent and the composite group name of the target storage agent can be different. While creating a host group, you can specify a custom name for the composite group that will be created. For EMC storage agents, two different attributes, the customcgname and the bsitecgname attributes are used for the source storage agent and the target storage agents respectively. For storage systems other than the EMC storage systems, the composite group name of the source storage agent and the composite group name of the target storage agent must be the same.

To create an asymmetric host group with EMC storage systems, run the following command:

ksysmgr add host_group <host_group_name>
      hosts=<host1[,host2,...]> | file=filepath
      [ha_disk=<ViodiskID>]
      [repo_disk=<ViodiskID>]
      [backup_repo_disk=<ViodiskID[,ViodiskID2...]> | backup_repo_disk=none]
      [mxn_pairing=<yes>][customcgname=<CgName>] [bsitecgname=<CgName>]
    add => ad*, cr*, make, mk
    host_group => hg, host_g*

For example:

ksysmgr add host_group <name> hosts=<hostname separate by coma> mxn_pairing=yes customcgname=<source_cg_name> bsitecgname=<target_site_cgname>

To create an asymmetric host group with storage systems other than EMC storage systems, run the following command:

ksysmgr add host_group <host_group_name>
      hosts=<host1[,host2,...]> | file=filepath
      [ha_disk=<ViodiskID>]
      [repo_disk=<ViodiskID>]
      [backup_repo_disk=<ViodiskID[,ViodiskID2...]> | backup_repo_disk=none]
      [mxn_pairing=<yes>][customcgname=<CgName>]
    add => ad*, cr*, make, mk
    host_group => hg, host_g*

For example:

ksysmgr add host_group <name> hosts=<hostnames separated by comma> mxn_pairing=yes customcgname=<source_cg_name>

While creating an asymmetric host group, you must specify the host names from both sites. You must not specify the hosts that are already paired. By default, the host group type is symmetric. For asymmetric host group, set the value of the mxn_pairing attribute to yes. Similarly, if you want to use workgroup, set the workgroup_support attribute to yes.

Behavior of the KSYS in the asymmetric host group configuration

In an asymmetric host group configuration, the KSYS subsystem dynamically determines the target host for a virtual machine. This mapping is determined based on the resource availability on the target site during the discovery operation. You can query a virtual machine to view the target host of the virtual machine. Run the following command to query the virtual machine:

ksysmgr q vm

An output similar to the following screen is displayed.

Name: sehXVZZ
UUID: <UUID>
State:  READY
Dr Test State: INIT
Host: <Host>
Priority: Medium
Skip_power_on: No
Homehost: <Home host>
DrTargetHost: <DR Target Host>

The DrTargetHost field displays the name of the host where a virtual machine will be moved during the move operation. You can also specify the target host of a virtual machine in the DrTargetHost attribute when you run the ksysmgr modify vm command. Otherwise, the KSYS subsystem updates this attribute automatically during the discovery operation. If the target host of a virtual machine has been changed, specify an empty value for the DrTargetHost attribute to allow the KSYS subsystem to automatically determine the target host of the virtual machine. Run the following command to set a target host for a virtual machine in an asymmetric host group setting:

ksysmgr modify vm <vmname[,vmname2,...]> | ALL host=<hostname> | ALL host_group=<host_group_name> | file=<filepath>
      [uuid=<uuid>]
      [homehost=<hostname>]
      [DrTargetHost=<hostname>]
      [priority=<Low|Medium|High>]
      [log_level=<0|1|2|3>]
      [skip_power_on=<yes|no>]
      [ha_monitor=<enable | disable>]
      [proactiveha=<enable | disable>]
      [vm_failure_detection_speed=<fast | normal | slow>]
      [blocklist_hosts=<hostname[,hostname2...]> | [policy=<add | delete>]]
    modify => mod*, ch*, set
    vm => lp*, vm

For example:

ksysmgr modify vm <vm_name> DrTargetHost=<host_name>

Note:

You cannot use the ksysmgr modify vm ALL host_group=<host_group_name> command with the blocklist_hosts attribute.
The DrTargetHost attribute is valid only for the asymmetric type of host group.
The type, symmetric or asymmetric, that is set while adding the host group, cannot be modified later.