Experiences with kernelcare/KSplice/etc.

[RTM]

Do any of you guys have any experiences with software that can hot-replace a kernel, like kernelcare and ksplice?

I am considering setting something like this up at work (primarily kernelcare, as that is relatively affordable), for some of the VMs where a reboot would result in jobs having to be completely restarted (can be multiple days worth of work).

I would appreciate any insight into this, like whether or not this type of software is even production ready.

 

[Mike]

I think, atleast 5 or 6 years ago, i used Ksplice to hot patch a kernel a few times, although i think it was free back then. Cool technology, although i would think fixing the real issue here would be more worthwhile no?

 

[sean]

Red Hat and SUSE have kpatch and kGraft respectively. Something will make it into the kernel soon. That doesn't help older kernels, but I wouldn't be surprised to see it backported to CentOS 7's kernel.

 

[RTM]

Red Hat and SUSE have kpatch and kGraft respectively. Something will make it into the kernel soon. That doesn't help older kernels, but I wouldn't be surprised to see it backported to CentOS 7's kernel.

I guess the question is, how much time will it take for Red Hat and/or SUSE to turn their respective software tools into something that is "production ready".

For that matter it would be nice if something like this becomes available to Debian and derivatives.
Ksplice has something for Ubuntu desktop and kernelcare promises Debian support in the future, but it's not quite there yet.

 

[RTM]

So I installed Kernelcare in a CentOS 7 VM the other day, it looks very usable.

A few details I have noticed(or read on their site):
- There seems to be "some" delay, from official release to release, how much is unknown and what reasons they have for the delay(compiling, testing etc.).
- As stated on their site, they only provide patches for security stuff and maybe critical bugs.
- Perhaps due to #1, updates does not seem to integrate nicely with yum, so I can still download updated kernels from that (I would prefer KC controlling that).
- It autoupdates every 4 hours, no other option in default config file than to disable autoupdate. Nothing that a cronjob can't fix though.

Overall these things appear to be minor issues, so I think its a quite useful product.
I for one am just waiting for a release of oVirt that supports EL7, then I can replace my ESXi installation with a solution based on EL7, oVirt and Kernelcare.