VMware incrementals increasing in size over time
Explain why VMware incremental backups increase in size over time.
When running an incremental forever backup strategy, the size of the incrementals increases over time, increasing backup times and decreasing retention.
This is most likely due to a known VMware bug, which will be addressed in the next major release of vSphere in 2013.
Install the agent for the virtual machine and back it up at the agent-level.