What is the difference between HA_MODE_SHARED and HA_MODE_SHARED_PAIR options available in Avi CLI?
Answer:
HA_MODE_SHARED and HA_MODE_SHARED_PAIR are ha_mode flags available in Avi CLI under serviceenginegroup properties.
| Field | Value |
+---------------------------------------+---------------------------------------------------------+
| uuid | serviceenginegroup-5d061595-426f-48bf-9683-a3ca95a5f1dd |
| name | Default-Group |
| max_vs_per_se | 10 |
| min_scaleout_per_vs | 2 |
| max_scaleout_per_vs | 4 |
| max_se | 10 |
| vcpus_per_se | 2 |
| memory_per_se | 2048 |
| disk_per_se | 10 gb |
| max_cpu_usage | 80 percent |
| min_cpu_usage | 20 percent |
| se_deprovision_delay | 120 min |
| auto_rebalance | True |
| se_name_prefix | SE1 |
| vs_host_redundancy | True |
| vcenter_folder | VM1 |
| vcenter_datastores_include | False |
| vcenter_datastore_mode | VCENTER_DATASTORE_ANY |
| vcenter_clusters | |
| cluster_refs[1] | N3K |
| include | True |
| cpu_reserve | False |
| mem_reserve | True |
| ha_mode | HA_MODE_SHARED
HA_MODE_SHARED option is equivalent to N+M elastic HA option available on Avi user interface. In this mode, each virtual service is typically placed just on one Service Engine, unless the scaleout-per-vs setting is changed to 2 or more.
HA_MODE_SHARED_PAIR is equivalent to active/active elastic HA mode available on Avi UI. In active/active HA mode, Avi Vantage places each virtual service on more than one SE, as specified by min_scaleout_per_vs parameter.
The default value for the parameter min_scaleout_per_vs is 2. The value for min_scaleout_per_vs is changed through Avi CLI.
If value for the flag HA_MODE_SHARED is set to true and value for the flag min_scaleout_per_vs is set to 2, then HA mode will work like active/active elastic HA mode as one virtual service is placed on more than one SE.
Changing HA modes using Avi CLI
Use configure serviceenginegroup option to change HA modes on Avi Vantage.
[admin:Controller-2]: > configure serviceenginegroup Default-Group ha_mode
Changing HA modes using Avi UI
To change HA mode using Avi UI, navigate to Infrastructure > Service Engine Group. Click on the edit icon at the right side to select various options for HA mode, available under High Availability & Placement Setting as shown in the below screenshot.
Note: The virtual service placement setting (compact and distributed) plays a very important role in spinning up SEs.
##Additional Information To know more about virtual service placement options on Avi Vantage and Elastic HA mode for Avi SEs, refer to Elastic HA for Avi Service Engines.