ballon driver

[prakash9339]

what is balloon driver how it will work

[Davoud Teimouri]

This is an innovative memory reclamation technique where the guest operating system is made aware of the host's low memory status. The guest operating system by default is not aware that it is running in a virtual machine and the amount of free host memory. The balloon driver is part of the VMware Tools installation. It communicates with the hypervisor directly which will set the balloon size based on the amount of host physical pages it needs to reclaim. The balloon driver then pins the pages in the guest free list and the hypervisor then reclaims the host physical pages which are backing them. If the guest operating system is under memory pressure, it will decide which guest pages to page out without any intervention from the hypervisor.

[tomtom901]

An important fact: If you do not install the VMware Tools, the vmmemctl (balloon) driver will not be installed, and ballooning will not be possible. ESXi has 4 memory management techniques:

1) Transparent page sharing: Eliminates redundant copies of memory pages by removing them from memory and creating a reference instead.
2) Memory ballooning: In times of contention, the balloon driver (comes with VMware Tools) will ask the guest OS for unused memory and returns this back to vSphere
3) Memory compression: After ballooning runs out, try compressing the memory (basically gzipping it).
4) Swap to disk / host cache: Swap memory to a disk of some sort.

So, without the VMware tools (vmmemctl) balloon driver installed, we will only have 3 memory management techniques. It skips ballooning and goes straight to compression.

[Kahonu84]

Wouldn't Google have been easier and faster?