At $WORK there’s been an increase in the failures of VMs on our provider (AWS) recently. It has been suggested that using a more reliable root filesystem might help here.
I first tested this locally – unmounting the root filesystem on Centos 7 VM resulted in a very different set of symptoms than we had seen in AWS. As I expected, it continued to respond to pings, but the other monitoring reported multiple failures. Conversely in the AWS instances, the host immediately stopped responding to pings (which causes our monitoring system to not bother asking about services).
While this favoured the null hypothesis, I want to try this on a monitored, AWS VM. However it won’t let me unmount the root filesystem (“umount: /: target is busy.”).
We only have access to the storage via the host or the AWS API. Is there another way I can break the root filesystem on a AWS Linux 2 VM? (read-only is not broken enough).
Kernel version is 4.14.327-246.539.amzn2.x86_64