When comparing ClickOS vs HaLVM, the Slant community recommends ClickOS for most people. In the question“What are the best unikernels?” ClickOS is ranked 5th while HaLVM is ranked 7th. The most important reason people chose ClickOS is:
More than 100 instances of ClickOS can be run concurrently while saturating only a 10GB pipe on an inexpensive server.
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Pros
Pro Can run a large number of instances concurrently and cheaply
More than 100 instances of ClickOS can be run concurrently while saturating only a 10GB pipe on an inexpensive server.
Pro Great performance
Benchmarks have shown that ClickOS has great performance. It boots quickly (averages at about 20milliseconds) and has very little delay (about 45 microseconds).
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 Has some complexity added because it's not based on a language with process isolation
Since C and C++ (with which ClickOS is built) have no language level isolation, ClickOS doesn't have process isolation either. Because of this, sensitive components have to be split into different nodes, isolated by either different virtual machines or different computers.
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).