Verify that the boot sequence of the virtual machine is such that the boot disk (OS hard disk) is placed before the removable disks.

If the sequence places the removable disks before the boot disk, the virtual machine may not reboot after an application failover. The reboot may halt with an "OS not found" error.

This issue occurs because during the application failover the removable disks are detached from the current virtual machine and are attached on the failover target system.

Verify that VMware Tools is installed on the virtual machine.

Install the version that is similar to or later than that available with VMware ESX 4.1.

Verify that you have installed VMware vSphere Client. The vSphere Client is used to configure and control application monitoring.

You can also perform the application monitoring operations directly from a browser window using the following URL:

https://<virtualmachineNameorIPaddress>:5634/vcs/admin/
application_health.html?priv=ADMIN

A prompt for the user account details will be displayed. You must enter the system user account details.

Verify that all the systems on which you want to configure application monitoring belong to the same domain.

Verify that the ESX/ESXi host user account has administrative privileges or is a root user.

If the ESX/ESXi user account fails to have the administrative privileges or is not a root user, then in event of a failure the disk deattach and attach operation may fail.

If you do not want to use the administrator user account or the root user, then you must create a role, add the required privileges to the created role and then add the ESX user to that role.

See Assigning privileges for non-administrator ESX/ESXi user account.

If you want to monitor the mount points, ensure that the volumes or mounts selected during configuration do not have multiple paths or drive letters assigned to it.

The Symantec High Availability Configuration wizard fails to configure monitoring if the selected mount points or a volume has multiple drive letters or paths are assigned to it.

If you have configured a firewall, ensure that your firewall settings allow access to ports used by Symantec High Availability installer, wizard, and services.

After configuring services, processes, and mount points for monitoring, if you create another service, process, or mount point, then these new components are not monitored as part of the existing configuration.

In this case, you can either use the VCS commands to add the components to the configuration or unconfigure the existing configuration and then run the wizard again to configure all the components.

In case the VMwareDisks agent resource is configured manually, care should be taken not to add the operating system disk in the configuration. The VMwareDisks agent does not block this operation. This might lead to a system crash during failover.

If VMware vMotion is triggered at the same time as an application fails over, the VMwareDisks resource may either fail to go offline or may report an unknown status. The resource will eventually failover and report online after the vMotion is successful and the application is online on the target system.

VMware snapshot operations may fail if VMwareDisks agent is configured for a physical RDM type of disk. Currently only virtual RDM disks are supported.

Non-shared disks partitioned using GUID Partition Table (GPT) are not supported. Currently only Master Boot Record (MBR) partition is supported.

VMwareDisks agent does not support disks attached to the virtual machine using IDE controllers. The agent resource reports an unknown if IDE type of disks are configured.

In case VMware HA is disabled and the ESX itself faults, VCS moves the application to the target failover system on another ESX host. VMwareDisks agent registers the faulted system on the new ESX host. When you try to power on the faulted system, you may see the following message in the vSphere Client:

This virtual machine might have been moved or copied. 
In order to configure certain management and networking features, 
VMware ESX needs to know if this virtual machine was moved or copied. 
If you don't know, answer "I copied it".

You must select "I moved it" (instead of the default "I copied it") on this message prompt.

You must not restore a snapshot on a virtual machine where an application is currently online, if the snapshot was taken when the application was offline on that virtual machine. Doing this may cause an unwanted fail over.

This also applies in the reverse scenario; you should not restore a snapshot where the application was online on a virtual machine, where the application is currently offline. This may lead to a misconfiguration where the application is online on multiple systems simultaneously.

If you want to suspend a system on which an application is currently online, then you must first switch the application to a failover target system.

If you suspend the system without switching the application, then VCS moves the disks along with the application to another system.

Later, when you try to restore the suspended system, VMware does not allow the operation because the disks that were attached before the system was suspended are no longer with the system.

While creating a VCS cluster in a virtual environment, you must configure one of the cluster communication link over a public adapter in addition to the link configured over a private adapter. To have less VCS cluster communication over the link using the public adapter, you may assign it low priority. This keeps the VCS cluster communication intact even if the private network adapters fail. If the cluster communication is configured over the private adapters only, the cluster systems may fail to communicate with each other in case of network failure. In this scenario, each system considers that the other system has faulted, and then try to gain access to the disks, thereby leading to an application fault.

VMware Fault Tolerance does not support adding or removing of non-shared disks between virtual machines. During a failover, disks that contain application data cannot be moved to alternate failover systems. Applications that are being monitored thus cannot be brought online on the failover systems.

For cluster communication, you must not select the teamed network adapter or the independently listed adapters that are a part of the teamed NIC.

A teamed network adapter is a logical NIC, formed by grouping several physical NICs together. All NICs in a team have an identical MAC address, due to which you may experience the following issues: