Why do we use a OS Base Image with Docker if containers have no Guest OS?

Since all Linux distributions run the same (yup, it’s a bit simplified) Linux kernel and differ only in userland software, it’s pretty easy to simulate a different distribution environment – by just installing that userland software and pretending it’s another distribution. Being specific, installing CentOS container inside Ubuntu OS will mean that you will get … Read more

What does Virtual memory size in top mean?

Virtual memory isn’t even necessarily memory. For example, if a process memory-maps a large file, the file is actually stored on disk, but it still takes up “address space” in the process. Address space (ie. virtual memory in the process list) doesn’t cost anything; it’s not real. What’s real is the RSS (RES) column, which … Read more