Kernel Update Best Practices
I manage several servers and recently ran into an issue with updating one of the kernals - after reboot I was completely locked out of the server - SSH keys and even console access would not work due to passwords not being recognised. I eventually solved that issue with the help of a datacentre root pw reset - though it was quite inconvenient to have to reset all keys and passwords.
The servers are all VPSs on KVM and either CLOUDLINUX 6.8/whm 6.2 or CentOS 7.3
My questions is;
1) Why would that have happened;
2) What is a quick run down of the "best practice" for kernal updates - there does not really seem to be an up to date methodology listed.
3) On one specific machine, I do not have access to snapshots - would a kernal update on this machine be very high risk? I do have WHM backup enabled - but I assume this is not going to contain the OS files!
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Hello, Rebooting a machine after a kernel update should not result in an ability to access the server. It's likely something else happened during the reboot that lead to the login credentials failing to work. Could you review /var/log/secure for the time this happened and see what shows up for the failed login attempts? ) What is a quick run down of the "best practice" for kernal updates - there does not really seem to be an up to date methodology listed.
Generally, upon installing the new kernel via YUM, you simply reboot the system so that it uses the new kernel.) On one specific machine, I do not have access to snapshots - would a kernal update on this machine be very high risk? I do have WHM backup enabled - but I assume this is not going to contain the OS files!
Kernel updates are not generally high risk, but it is possible for unforeseen events (e.g. file system errors) to result in the server failing to boot upon issuing the reboot command. Thank you.0 -
kernel updates are very safe they do not cause any issues. I generally use yum install kernel which installs the new kernel keeping the old kernel as it is. Yes this can cause lot of having lots of old kernel but you can keep clearing old kernels when your /boot is full 0
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