An administrator notices that 8 out of 10 virtual machines have memory ballooning and swapping. However, virtual machine 9 is not ballooning or swapping and virtual machine 10 is not ballooning but is

When a VM has a 100% memory reservation, every page of its configured RAM is guaranteed by physical memory, leaving ESXi with no pages it is permitted to reclaim through ballooning or swapping, which explains why VM 9 shows neither technique.

A memory limit caps active usage but does not remove the balloon driver or prevent ballooning; a VM with a limit would still balloon before swapping occurs.

High memory shares give a VM priority during contention but do not fully protect its pages from reclamation, so the VM could still be required to balloon under sufficient host memory pressure.

The balloon driver lives inside the guest as part of VMware Tools; when VMware Tools is absent, the driver does not exist and ESXi cannot use ballooning, so it skips that reclamation tier and immediately uses host-level swapping to free memory.