A few years ago, virtual server backup was a pain point for many IT teams. Today, there are a variety of virtual machine (VM) backup software products to ensure data on virtual servers is protected.
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In some cases, virtualization can also benefit the data protection process. For example, many data protection products allow users to run an application from a backup instance of a VM following an outage of the primary virtual machine. This gives users access to data and applications while the primary VM is restored.
So, the outlook on virtual server backup is decidedly brighter these days. However, there are a number of important aspects to consider when it comes to VM backup software.
How VM backup works
There are a number of ways virtual servers can be backed up. Some shops still prefer to use traditional backup software and install agents on each VM. This is fine if you are protecting a small number of virtual machines. However, if you have hundreds of VMs to protect, this approach can become unwieldy.
The biggest issue with this approach is resource contention. Traditional backup software was designed around the idea that a single physical server would run a single application. With virtualization, there can be many applications running on a single physical server. This can lead to competition for compute resources and slow application performance during backup. This approach also requires shops to treat each VM as a discrete client with separate licensing costs -- depending on the number of VMs you back up, this can become an expensive proposition.
Many shops use VM-specific backup software such as Veeam Backup & Replication or the VM backup functionality included with many traditional backup software products. For example, legacy backup software vendors like Commvault, Symantec and EMC offer VM-specific backup options today.
VM backup software products take advantage of APIs provided by the hypervisor vendor, such as VMware's vStorage API for Data Protection. This allows the backup application to put the virtual machine into a backup-ready state, known as quiescing the VM, before taking a snapshot and using it to create an image-level backup. Users can restore an entire VM from the image. Today's software is also sophisticated enough that it can retrieve and restore individual files from the VM image.
One of the newer and more interesting features of VM backup software is recovery-in-place or instant recovery. The latter name is a little misleading because recovery is not truly instantaneous. While recovery-in-place should not be mistaken as a high-availability technology, it does allow users to return to operations quickly especially when compared with a traditional server restore.
Virtualization lets users move workloads to balance the load on storage and compute resources and to improve performance. This capability also makes a VM easier to recover. Recovery-in-place allows a hypervisor to mount a backup instance of a VM and to get applications up and running quickly while the primary VM is restored. This is a very useful tool, but there are a number of things you should be aware of before using recovery-in-place.
As noted above, recovery-in-place is not instantaneous and applications will see some downtime. Most backup vendors claim this technology can have an application up and running in the backup environment within a few minutes. But it is not an automated process. While the exact method will differ from product to product, recovery-in-place requires manual intervention.
For example, when using Symantec's NetBackup Instant Recovery for VMware, the process is as follows:
- Users run a command to access the VM from its backup image.
- NetBackup mounts the image as an NFS data store and creates a temporary data store on the ESX host where the VM will be restored.
- While running from the backup VM, new write requests are directed to the temporary data store while the NFS data store is read-only. This keeps the backup in a pristine state.
- Storage vMotion is used to copy the VM data from the NFS data store to the temporary data store, while vSphere Client is used to merge the VM snapshot files.
- Users run another command to unmount the NFS data store.
Performance is another important consideration. Since backup hardware is not designed for high-performance applications, users should expect to see a performance dip while using recovery-in-place. However, lower performance is better than application downtime. If you plan to rely on recovery-in-place, you will need to ensure that your backup server has enough compute power to run your application(s) at a reasonable performance level.
VM backup software adoption
A 2014 survey of our readers revealed that 46% of respondents have "no problems" backing up VMs. Many shops use VM-specific backup software (28%) or VM backup options from a traditional backup software vendor (29%). Those numbers are up from the 7% and 11%, respectively, reported in 2012. In addition, the percentage of those surveyed that rely on traditional agent-based backup for VMs has fallen to 20% versus 29% in 2012.
The virtual server backup approach an organization takes will be dictated by its specific needs. The good news is that there are plenty of options available.
New VM backup software options simplify recovery
How virtual machine backup tools integrate with cloud backup/disaster recovery
The best backup software for virtual machines