Incremental Backup of Virtual Machines: time of being part of your strategy

Backup has always been one of the must-have IT capabilities, especially in enterprise network. It has to be done to ensure that the IT system can always be recovered from a failure or disaster condition, and also to ensure that users will not lose their important data and access to services. A good backup strategy should include an incremental backup in its plan. It is important to have an incremental backup on Virtual Machines (VMs) to ensure continuous backup while still maintaining efficiency in the process. Of course, popular virtualization platforms like VMware vSphere or Microsoft Hyper-V has been made to support incremental backup.

Incremental backup is a type of backup that only copies part of the data that are changed since the successful backup. It works differently with the typical full backup, where the whole data parts were copied. To help better understanding on how each type of backup works, see this example:

For example, a data contains three letters “X-Y-Z” was fully backed up yesterday. Today, the data is modified so now we have four letters “W-X-Y-Z”. If we then perform another full backup, it will copy the whole data “W-X-Y-Z”. But if we perform an incremental backup instead, it will only copy the “W” part of the data. Obviously, copying only the “W” part of the data will consume less disk space compared to copying the whole “W-X-Y-Z” data. Moreover, we already have the “X-Y-Z” part backed up previously, so we don’t need that part to be backed up again. With this way, we can save disk space used to store the backup. Incremental backup is also processed faster, as the size of the backup data is smaller. And because of the smaller size, it gives less burden to the network.

The importance of incremental backup for VMs

We all know that in this virtualization era, administrators are given the option to do the backup at the virtualization layer rather than the traditional backup at the OS level. The option to perform backup at the virtualization layer is easily preferred because it reduces the service disruption caused by the backup process that usually eats up a lot of resources on the OS. This also adds more flexibility to the process as the administrator can easily restore a VM by simply mounting the virtual disk to a host data store. Technology like deduplication, snapshot, and replication also helps in making the backup process more efficient. However, in the contrary to all the facts mentioned above, backup data could consume lots of disk space if the administrator doesn’t plan it correctly, and ended up with high investment on storage infrastructure. One of the strategies to avoid this is by implementing incremental backup.

The common best practice in VM environment is to do incremental backup more often than the full backup. For example, the full backup can be done on the VM only on the weekend while the incremental backup can be done every day during weekdays. It makes sense to do the full back up only on the weekend as, usually, it requires more time and network bandwidth. On the other hand, incremental backup performed during the weekdays to catch the changes made on the VM after the last successful full backup.

There was a concern in the past in terms of restoring a backup resulted from incremental backups. At first, the initial full backup data needs to be restored, then followed by the incremental backup data. With this way, restore task requires more time and very error prone because the incremental backup data needs to be restored in the same order they were backed up. However, this was in the past. In today’s technology, most of the backup software has the capability to consolidate the backup data. So, for example, if we have performed a full backup followed by three incremental backups, the result will be combined into a single backup file that can be restored as a whole. In VMware, this feature is called VMware Consolidated Backup (VCB) while Microsoft doesn’t have a specific name but simply refer it as a merged checkpoints/snapshots.

Today, there’s no more reason to not using the incremental backup. Incremental backup has been proven to save cost of storage infrastructure as it can maintain the backup to stay current, but with very efficient, non-disruptive process. Iperius supports incremental backup as well as consolidation on the incremental backup data on your vSphere ESXi or Hyper-V host.

See how to achieve an incremental backup of virtual machines with Iperius here.