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Possible Duplicate:
Reloading a kernel “live” in CentOS / RHEL 6

How can i update kernel on Centos without reboot .?

I found ksplice but it is not supported for Centos.

Regards,

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Linuxstartway
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  • KSplice is really the only option. If KSplice doesn't support CentOS or RHEL, you're pretty much out of luck. – larsks Mar 06 '12 at 20:53
  • CentOS lets you upgrade any time. But you have to reboot to activate the new kernel. What part of the boot-process is actually causing you headaches? – Nils Mar 06 '12 at 20:55
  • if you need solid uptime, think about using openbsd . You get a lot less kernel updates. – The Unix Janitor Mar 06 '12 at 22:55

2 Answers2

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From man kexec:

kexec is a system call that enables you to load and boot into another kernel from the currently running kernel. kexec performs the function of the boot loader from within the kernel. The primary difference between a standard system boot and a kexec boot is that the hardware initialization normally performed by the BIOS or firmware (depending on architecture) is not performed during a kexec boot. This has the effect of reducing the time required for a reboot.

To install it: yum install kexec-tools

Nils
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    It minimize the reboot process. But still there is a down time and not as efficient as KSplice. – Linuxstartway Mar 06 '12 at 21:42
  • Look at 3dinfluece below. If this is a production server KSplice is not enough to keep the system up to date. BIOS-updates often also require a reboot (as do some other firmware-updates). So there would be better a second server able to take over the sessions. – Nils Mar 06 '12 at 22:12
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With KSplice not supporting your OS you're out of luck.

user9517
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  • @larsks Centos is not supported by Ksplice at the current time http://www.ksplice.com/pricing – Linuxstartway Mar 06 '12 at 21:07
  • @Nils I want to update the kernel without down time, If i'm using a production server it will be a problem to reboot the server every time i update the kernel. – Linuxstartway Mar 06 '12 at 21:13
  • The CentOS-Kernel is binary compatible to the RH or unbreakable Linux Kernel. So what? – Nils Mar 06 '12 at 21:17
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    @RamyAllam if uptime is that important then you need to come up with a HA strategy that involves more than one machine with failover. That way you can always take one off line for maintenance. – 3dinfluence Mar 06 '12 at 21:18
  • How does KSplice replace active running kernel modules? – Nils Mar 06 '12 at 21:18
  • @Nils In order to use the RH release, It required access key from ksplice.com and redhat.com. So that i can not use the RH rpms on Centos – Linuxstartway Mar 06 '12 at 21:37
  • You can install it on CentOS, it just won't run `The Ksplice Uptrack for RHEL trial provides access to rebootless updates for RHEL 5 and 6 systems only. If you have any questions, please contact ksplice-support_ww@oracle...` – user9517 Mar 06 '12 at 22:08
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    @RamyAllam so you open a direct channel via internet for kernel-updates? I hope these updates are signed (as are RPMs). – Nils Mar 06 '12 at 22:08
  • From Ksplice FAQ: http://www.ksplice.com/uptrack/faq . Does Ksplice Uptrack use cryptography? Yes. All network traffic is encrypted, and all updates are cryptographically signed. – codewaggle May 19 '12 at 20:13