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Over the past few years, it has become much more common for organizations to operate multi-hypervisor environments. This mix of hypervisors sometimes results from mergers and acquisitions, but in other cases it may be due to shrinking IT budgets forcing IT staff to adopt less expensive technology. Whatever the reason, environments with multiple hypervisors are quickly becoming the norm.
Operating a multi-hypervisor environment introduces a number of logistical challenges, not the least of which is backup and recovery. IT professionals must carefully consider how a mix of multiple hypervisors will affect their disaster recovery plans. Here are three main challenges that can catch IT pros off guard.
Inadequacies with backup applications
Not that long ago, running multiple hypervisors meant having a separate backup application for each hypervisor. Today, some of the major backup vendors allow you to back up multiple virtualization platforms using a single backup application. Even so, such products do not always provide identical levels of coverage for the various hypervisors. For instance, a backup application might have very rich VMware support, but minimal support for backing up Hyper-V virtual machines (or vice versa).
Organizations considering a backup application designed to work with multiple hypervisors should check the specific hypervisor versions that are supported. Some backup applications, for instance, do not yet support vSphere 6.
Instant recovery support
The single most important backup-related feature introduced in the last few years is instant recovery. This allows you to bring a virtual machine (VM) online immediately after a failure without the need for a traditional restoration. The technology features a dramatically lower recovery time objective, allowing users to get back to work almost immediately.
Although instant recovery has become the must-have feature for backup applications, it can be problematic in organizations running multiple hypervisors because this feature depends on disk-based backups. If an organization uses disk-based backup, the latest recovery point is available online, without the IT staff having to mount a backup tape. Because VM backups are readily accessible on a disk-based backup, the backup software can direct a hypervisor to mount a VM directly from the backup. Prior to doing so, a snapshot is created so that any write operations are isolated within a dedicated differencing disk and do not impact the integrity of the backup.
Backup vendors have their own way of doing things. Regardless of the specific method a backup vendor uses to enable instant recovery, it cannot work without a hypervisor. With that in mind, imagine trying to use an instant recovery feature in an environment with multiple hypervisors. Depending on how your backup software works, it is possible that instant recovery might be enabled for one virtualization platform, but not another. It is also possible that enabling instant recovery in a multi-hypervisor environment will require you to back up each virtualization platform separately.
Distributed backup applications
Distributed backup applications can also complicate disaster recovery in multi-hypervisor environments. Imagine for a moment that you have an application that not only spans multiple VMs, but multiple hypervisors. How do you protect that application?
Unless you are running guest backups, your backup software would not only need application awareness, but it would also have to natively support each hypervisor. If you needed to carry out a full VM restoration, the backup application would have to determine which virtualization platform each application's VMs were running on. The backup software must be able to perform a crash-consistent recovery of the distributed application despite some of the application's VMs running on different hypervisors.
It is not impossible to protect VMs running on multiple hypervisors. Doing so requires a good understanding of which VMs are running in each environment, what the recovery requirements are for each virtual machine, and whether or not your backup application can deliver those capabilities. Although not convenient, it is sometimes more effective to adopt separate backup products for each environment rather than trying to make a single backup application handle all your backup needs.
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