When comparing OSv vs HaLVM, the Slant community recommends OSv for most people. In the question“What are the best unikernels?” OSv is ranked 3rd while HaLVM is ranked 7th. The most important reason people chose OSv is:
OSv is able to boot in less than a second.
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Pros
Pro Quick booting
OSv is able to boot in less than a second.
Pro Amazing performance
Since OSv is created to run one single application on top of a hypervisor, it offers great performance and speed.
Pro Supports multiple platforms
OSv can run applications written in multiple programming languages and that run on multiple different platforms. Such as Java, C, Ruby, Node and Scala. With support for other languages on the way.
Pro Highly secure
What HaLVM does in simple terms is to provide only the minimal needed for an app to run. It provides only the required network and hardware drivers needed to execute.
Using this approach it minimizes the attack surface for potential hackers since they don't have any shell to log into or any other insecure cruft that other deployment methods, such as full operating systems have.
Cons
Con Can only run one application at a time
Since it tries to have maximum performance, OSv can only afford to run one application per hypervisor at a time.
Con Compiling from source can be problematic
Usually with cutting-edge software the compilation process never really goes as expected. Same is with HaLVM as well.
You may need to install additional libraries that are probably missing or even tweak configurations here and there. So it would be best to avoid this process if you don't feel comfortable enough with compiling from source. So you have to stick with the package manager of choice (if it's available for the particular Linux distro you are using).