Configuration of cluster and fault recovery system in virtual environment

The high availability of Virtual data Center (HA) is a multi-level task involving online backup (live backup), recovery functionality, or clustering. In this article, we will explore how to configure the cluster (cluster) in a virtual environment, and establish a fault recovery system (failover structure).

The high availability of virtualization has two levels. We can operate at the child level, rely on the OS and apply disaster recovery capabilities, or operate at the host layer to face a new set of problems.

The process of performing an HA configuration at the child layer is almost as much a technical problem as in a physical machine environment. For example, set up a static MAC address for each virtual network interface. In addition, there are a number of constraints that need to be breached, depending on the selected virtualization platform and the HA software. However, virtual cluster creation is basically complete and can even create a hybrid (mixed) virtual cluster. In a hybrid virtual cluster, one or more nodes are virtual machines and the other nodes are physical machines.

The high availability of hosts is more necessary, but also more complex. In such cases, in the case of failback, the virtual machines running on the host must be replicated to another host, and the virtual disk and virtual memory modifications are replicated to maintain continuous synchronization. This operation has the same problem as an online backup, and it is more complex and needs to be done as quickly and as much as possible.

In this way, Vizioncore once again became the protagonist. It has a esxreplicator that can replicate a running virtual machine from one VMware server to another VMware server, and does not require a centralized storage device. Unfortunately, this product can not handle network modification (network modification), while performing failback needs to use network modification, so we can only manually switch the error host and cold backup (cool standby) host.

VMware itself also offers a more powerful solution, offering ESX Server 3 and VirtualCenter 2, which is a vmotion based recovery option. VMware ha does not resemble Vizioncore Esxreplicator, which automatically restarts virtual machines in the wrong host. Unfortunately, VMware ha is very laborious in configuration. It must have VirtualCenter and vmotion, and the virtual machine must be stored in a Fibre Channel SAN environment, otherwise it will not work.

Other high Availability methods

On the other hand, the P2V migration Tool can help us perform P2V migrations. Therefore, we can configure the P2V migration Tool to replicate the virtual machines to other hosts.

In this case, Platespin is a better choice. It provides the dynamic migration capabilities of the Windows operating system (live migration). In addition, this technology can also be used for disaster recovery. Unfortunately, Platespin, like Vizioncore, cannot handle every aspect of recovery, so we have to intervene manually.

While it is a good idea to use failback, the most desirable method of HA configuration is undoubtedly a cluster. In a cluster, multiple hosts serve as an execution front-end for shared virtual machines. If one of the hosts fails, no service interruption is caused. The virtual machine is always available because there are other hosts that can work properly.

Using the virtualization platform's own capabilities or third-party solutions, we can perform clusters at the host layer.

For example, in Microsoft Virtual Server, Windows is the host operating system, and Microsoft allows the virtual physical node cluster to be performed through the Cluster service.

Instead, Vmwareesx server does not have such a feature. However, it has some external solutions to accomplish this task, such as Symantec Veritas Cluster Service. The recent release of Rainfinity by EMC has allowed us to see the hope that one day Rainwall technology will eventually be used to implement ESX clusters.

At present, the virtualization cluster solution is far from mature enough, and must be rigorously tested before it is adopted.