Is it a good idea? Well, there is a VMware KB article which talks about the Disabling the balloon driver rather outdated. IMHO I don't see much interest in doing that. This KB article provides the step-by-step to disable the balloon driver in a VM.
But they emit a warning which says:. Here is an overview from the lab. You can also use vSphere Client to check if memory gets ballooned or not. VMware Ballooning isn't the only technique of memory reclamation. There is also other techniques such as VMware Transparent Page Sharing TPS which is a proprietary solution to transparently share memory pages between virtual machines and eliminating redundant copies of memory pages.
Then there is memory compression where ESXi will compress the memory before the need for swapping bad, worst to happen. But we might talk about those in one of our future posts.
If you are over-committing your hosts then this is an important topic to review. With our short blog post, we give you the idea how it works and where to look at the metrics, but one must study further to get the whole picture how all memory management techniques work within VMware infrastructure. Connect on: Facebook. Feel free to network via Twitter vladan. Also, ballooning will not work if your virtual machines are using all of their memory by applications within the virtual machine, this is commonly noticed in applications such as databases.
Ballooning can also become a problem if it's relied upon too much by the hypervisor. In an ideal situation, there would be no ballooning taking place. This would indicate a healthy environment. Ballooning would only commence if there is too much demand for memory on the host, in other words when the ESXi host does not have enough free physical memory to allocate to virtual machines. If ballooning is happening all the time then a performance issue can start on the host.
Many ballooning operations could cause additional CPU cycles to be used to perform the ballooning operations. This, in turn, could reduce the amount of physical CPU available to virtual machines on the host. After esxtop loads, hit the m key then the f key. The MCTL? If this value is zero then the ballooning driver is unlikely to be installed, or perhaps the virtual machine's memory is fully reserved.
You can also check for memory ballooning within the vSphere client. Once they have loaded, change the View to memory. Within this view the chart legend will show you which line is allocated to Ballooned memory , hopefully, this is showing a zero value for your host. This is a better option than manually reinstalling VMware tools with the ballooning driver unselected because this is harder to manage. In general, you wouldn't want to disable memory ballooning but if you have some applications or virtual machines that can feel the effects of ballooning then reserving all their memory is a good option.
Also, remember that reserving all memory on a virtual machine will ensure that hypervisor swapping will not occur since the memory has been reserved up-front. VMware's ESXi hypervisor does a great job in allowing overcommitment of memory for virtual machines.
This has a huge cost saving since many virtual machines can be deployed to a single ESXi host. On my test box the calculation is: 32GB - But take a look at the top output below: Notice that top says I have only MB free and that a whopping If you look through the process list there is no indication where this memory went.
What is happening here is that the VMWare balloon driver has consumed over 20GB of memory because this virtual machine is on a VM host that is over committed on memory. Where the memory went is essentially invisible to the standard utilities because it has been allocated directly in the kernel instead of to a normal process.
If you have access to the VMWare console you can see how much memory the VMWare host has asked the guest to balloon but it would be really nice to be able to see this from the guest since often the group managing Access Manager does not have access to the host console.
Fortunately, there is a VMTools utility, vmware-toolbox-cmd, that lets you see how much ballooning is taking place. Note that this value will go up and down as memory conditions on the host change but that Linux will continue to show the memory as used until the guest is rebooted. Tags: memory. How To-Best Practice. Comment List. Related Discussions. Resources Support. Page file swapping it is the OS that decides what pages to swap to disk!
To understand ballooning we would have to take a look at the following picture: This picture shows the three levels of memory in a virtual environment. Lets take a high level example: Inside a virtual machine you start an application. For instance solitaire solitaire as an application will ask the guest operating system in this case windows for memory.
You play solataire for a few hours. And then you close it down.
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