I want to have a KVM virtualized server with few VMs (with different Guest OSs) in production. Now when I want to install kernel/package updates for the host machine, how to restart the hypervisor without corrupting any VM data? (when there are some SQL/disk write is happening on the VMs)
I know this is a very simple question but I mainly want to know if KernelCare should be the best option for the host to keep updated. I am looking at no data corruption/any such serious issues but minimum interruption for the VMs are OK (in application hosting server environment).
Best Answer
The best bet for upgrading servers is to use live migration. Have a spare host which is given a fully upgraded software stack, then live migrate all running VMs to that host. Now you can safely upgrade & reboot the original host. This is how most public clouds handle their host upgrades without introducing downtime to their customer VMs.
Of course the guest VMs need their own software upgrades & reboots at some point too.