Based on information received from VMware Support, one of the most common reasons a support request (SR) for a backup issue is opened stems from virtual machine (VM) snapshots. The majority of backup and recovery solutions utilize the vSphere APIs for Data Protection (VADP), which leverages VM snapshots to perform backups. However, if a VM has one or more existing snapshots, this can cause backup failures. Many solutions handle this gracefully. Others provide nice, descriptive warnings like the one from vSphere Data Protection (VDP) shown below and, unfortunately, there are a few products that do not provide clear indication of why there was a failure.
Moral of this short story: If you are seeing backup failure on one or maybe a few of your VMs, one of the first things you should check is whether the VM has an existing snapshot. In a few, rare instances, I have seen a VM that has an existing snapshot, but it does not show up in the snapshot management user interface (UI) of the vSphere Web Client. If you suspect this is the case, here is a simple workaround: Take (another) snapshot. Once that process has completed, use the Delete All option to consolidate all of the snapshots. Then, retry your backup.
Proper snapshot management and clean-up has always been a best practice and this is one more reason to follow that best practice. Here are a couple of VMware Knowledge Base (KB) articles that help with VM snapshot management and clean-up:
Speaking of best practices – if you are going to be at VMworld next week, here are a few sessions related to backup and recovery that include best practices:
BCO4756 VMware vSphere Data Protection (VDP) Technical Deep Dive And Troubleshooting Session
BCO5041 vSphere Data Protection – What’s New and Technical Walkthrough
BCO5162 Implementing a Holistic BC/DR Strategy with VMware – Part Two
BCO5851 VMware Backups That Work – Lessons Learned and Backup Performance Tuning Based on Extensive VADP Benchmark Testing
I am sure there a more sessions that contain some backup and recovery best practices so be sure to search the VMworld content catalog for more. The list above is simply to get you started. Hope to see you at VMworld next week!
