Sorry for bringing up this old thread as I found some in-consistancies in some of the theories above...
I have a Physical server with 72GB RAM and 4x 4core CPU.
- running 5 VMs with total 12vCPUs (2 vCPUs x4 VMs + 4vCPU x1 VM) and 38GB RAM (4GB x2 VMs + 8GB x2 VMs + 6GB x 1 VM)
- one of the 5 VMs is running Win7 64bit (4v CPU and 6GB RAM)
The VM that I noticed with ballooning is the Win7 64bit VM (running Acronis).
When the backup jobs started I noticed the performance chart of the VM (approx 45 min) :
- RAM usage was a U shaped, starting from 6GB , dropped to 3GB after 15 min then back up to 5.5GB
- RAM Balloon was a n shaped, started from 4GB, dropped to 3.5GB but remained there till almost when RAM usage went 4GB, then dropped to 0.
- CPU chart shows violent swings between 10% and 30%
So what was the ballooning for ?