VMware
How hot-add works? Like actual works
Hi everyone, i searched the Internet try to find how actually hot-add works? By that i mean not options and configuration, no, i mean the underlying technology, how you can change the CPU and the RAM while the VM is running without crash it and what make me spending around how it detect it and its still live. Coz ok i know that the roles of the real world doesn’t apply on the Virtualization word but this also destroys the concept i know of how the OS works.
Can anyone help me by explaining how it works under the hood, i don’t want to know more about the how the enable it, i need to understand the underhood technology
View Reddit by ko0oke – View Source
Ready to blow your mind? Many physical servers support hot-add as well for both RAM and CPU. It’s just baked into the design/spec. Not a whole lot different than inserting a USB device. The OS is told new hardware is available, some PCIe init stuff happens, and now you’ve got more compute/RAM.
Search for hot swapping instead. Hot-add is just what VMware calls it.
Starter on some of the technical bits.
http://heim.ifi.uio.no/~knuto/kernel/4.14/core-api/cpu_hotplug.html
watch this from 43:55: https://videos.vmworld.com/global/2019/videoplayer/29526
The video is about vMotion, but they also cover “fast suspend resume” which is also used by hot add. Essentially ESXi creates a shadow vm with the new configuration and switches over.