This content is part of the Essential Guide: Cut data center sprawl to improve IT capacity

Strategies for combating zombie VMs

Zombie VMs are real, but they don’t have to be as scary as they sound. With proper planning and the right tools you can prevent shambling hordes of wasteful servers.

The idea of zombies in your data center sounds like something a sleep-deprived sysadmin would dream up, but there is such a thing as zombie VMs. In a virtual environment, a VM that continues to shuffle along in the background doing no significant work but still ‘living,’ is sometimes called a zombie VM (think George Romero’s slow, plodding monsters rather than the hyped-up bundles of rage that wanted to chomp Brad Pitt).

Often, these VMs once led perfectly normal, fulfilling lives as test or development machines but, for whatever reason, they’ve been forgotten, abandoned or just ignored. One or two resident zombies in your infrastructure usually isn’t a problem. If you’ve learned anything from The Walking Dead, you know it’s easy to pick off a couple of those clumsy fools (assuming you’re not an ancillary character). It’s only when you’re faced with hordes of useless bumbling virtual machines that you start to see a real problem. Luckily, zombie VMs won’t attack and infect other VMs in your infrastructure. However, they can waste valuable computing resources that could be freed up for more important workloads.

Where do zombie VMs and VM sprawl come from?
The first step in combating zombie VMs is knowing where they come from and how they can affect your environment. Most zombie VMs are simply temporary virtual servers that have been forgotten due to lax tracking procedures.

How to tell if you’re at risk for zombie VMs
If you don’t have a well-defined strategy for tracking VMs, you’re at risk for an all-out zombie siege. After all, if you don’t know what’s running in your environment, you will have  no way of knowing whether a VM should be there or what it’s doing.

Private cloud capacity planning can reign in zombie VMs
Hunting down and eliminating zombie VMs is especially important in a private cloud where end-users have the ability to provision their own servers. You need a strategy for tracking and reporting on VM creation and use.

Use lifecycle management tools to kill off zombies
Spoiler alert: You don’t need any actual weapons to kill zombie VMs. Please don’t shoot your servers. Lifecycle management tools and policies that track VMs will help you keep zombies from getting out of hand.

Controlling sprawl and zombie VMs in a cloud
Cloud providers are at increased risk for sprawl, and failing to combat zombie VMs can lead to huge inefficiencies and customer complaints. Read these four myths about VM sprawl in a cloud environment.

Dig Deeper on Preventing virtual machine sprawl

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