Nutanix NCP-MCI-6.5 - Nutanix Certified Professional - Multicloud Infrastructure (NCP-MCI) v6.5 exam

An agent VM is a special type of VM that is used for running services or applications that are not affected by high availability (HA) events or host maintenance. An agent VM is never migrated to any other host in the cluster. If an HA event occurs or the host is put in maintenance mode, agent VMs are powered off and are powered on on the same host once that host returns to a normal state. This behavior is different from regular VMs, which are migrated to another host in the cluster if possible, or restarted on the same host if not possible1.

Therefore, during an AHV upgrade, an administrator may find that a critical VM was powered off rather than migrated to another host if the VM was marked as an agent VM. This can be done either from the Prism web console by selecting the Use this VM as an agent VM option in the Update VM dialog box, or from the aCLI by using the vm.create or vm.update commands with the agent_vm=true parameter2. To avoid this situation, the administrator should ensure that any critical VMs are not marked as agent VMs before starting the AHV upgrade.

According to the How to use the cvm_shutdown script web search result3, the cvm_shutdown script signals HA when shutting down the CVM (Controller VM) to forward the storage traffic to another healthy CVM. Instead of using sudo shutdown or sudo reboot commands, this script should be used to minimize I/O hits in user VMs running on the present hypervisor host. The cvm_shutdown -P now command will initiate the shutdown process on the CVM immediately. Therefore, if the administrator needs to perform an orderly shutdown of the CVM, they should execute this command from the CVM.

Port 389 is the default port for LDAP without SSL encryption. Port 636 is used for LDAP over SSL (LDAPS). Port 3268 and 3269 are used for Global Catalog (GC) and Global Catalog over SSL (GCSSL), respectively2.

According to the web search results, one possible cause of inter-VM communication failure between hosts is that the switch is not configured to allow VLAN 15 traffic. VLAN 15 is the default VLAN ID used by AHV for internal communication between CVMs and hosts. If the switch blocks or drops VLAN 15 packets, it will prevent inter-VM communication across hosts4. To enable full inter-VM communication, the administrator should update the switch to specifically allow VLAN 15 traffic on the ports connected to the AHV hosts.

According to the web search results, Distributed Storage Fabric (DSF) is the scale-out storage technology that makes HCI and cloud possible45. DSF pools the storage devices that are directly attached to a cluster of servers and presents them to applications across a variety of storage protocols4. DSF also manages and protects data by a fine-grained, distributed metadata system that ensures uniform distribution of data throughout the cluster to eliminate hot spots and speed up rebuilds

One of the possible reasons for a cluster to transition out of NearSync is insufficient network bandwidth between the source and target clusters. NearSync requires a minimum network bandwidth of 10 Mbps per VM for replication3. If the network bandwidth is lower than the required amount, the replication of recovery points may take longer than the configured RPO, resulting in an Out of NearSync condition. To address this issue, you can increase the network bandwidth between the clusters or reduce the number of VMs protected by NearSync4.

References: 1: Stargate - Nutanix Bible 2: Nutanix Cluster Architecture Overview - Nutanix Bible 3: NearSync Disaster Recovery (RPO <= 15 minutes) - Nutanix Support & Insights 4: Transitioning in and out of NearSync - Nutanix Support & Insights

According to the Nutanix Prism Central Guide, to configure a syslog server in Prism Central, you need to specify the transport protocol (TCP or UDP) and the IP address/port of the syslog server.