I don't really think ksplice has garnered much love from upstream. I for one, know that rpm based distros don't support it. Soham On Tue, Nov 19, 2013 at 12:52 AM, Mandeep Sandhu < mandeepsandhu.chd@gmail.com> wrote:

Yes, Ksplice offers this feature. Though check with them if your specific distro is supported. Or if you're compiling your own kernel then I guess you'll have to send them the new image which they convert to a reboot-less image which can be applied to a running system.

-mandeep

On Tue, Nov 19, 2013 at 10:55 AM, Shraddha Kamat <sh2008ka@gmail.com> wrote:

...

Is it possible to keep the kernel updated to upstream without ever rebooting the system ? Ksplice ??

Regards, Shraddha

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Vladis, I hear ya and agree to that. Problem is I have seen big and by big, I mean biggggggggg infrastructures asking for ksplice since certain sales people of certain company introduced them to the utopia that is called downtime-less-patching-and-upgrading. And obviously, if you have worked with the CLI a bit less than most of us have already had, you get the sweet inclination to go with sales and you know, voila. On Tue, Nov 19, 2013 at 2:16 PM, <Valdis.Kletnieks@vt.edu> wrote:

On Tue, 19 Nov 2013 09:48:27 -0500, Soham Chakraborty said:

...

I don't really think ksplice has garnered much love from upstream.

The most common word used upstream to describe ksplice is "bletcherous".

The reason it's disliked is because it's a poor solution for the problem. Although ksplice-like technology was used for years to upgrade telco switches on the fly, that was motivated by two major factors:

1) Nobody at a telco wants to drop dial tone while a switch reboots. 2) Telco switches are building-sized and expensive, so HA failover wasn't a realistic option.

Although the first is still an issue for many sites, there's little or no justification in 2013 for the second.

If you're in the sort of environment where you really need the sort of uptime that drive you to consider ksplice, you *really* should be doing load balancing and HA failover with heartbeats - that will not only allow you to actually reboot each server cleanly, but *also* protect you against blown DIMMs, crashed system disks, and all the *other* whoopsies that can cost you one or two nine's of reliability.

Seriously - if you can't afford the downtime to reboot, youy can't afford *NOT* to be doing a full HA configuration - and possibly looking at geographic separation of the hot failover site.

Sure, sure - I do. I actually adore it ;) On Wed, Nov 20, 2013 at 12:58 PM, <Valdis.Kletnieks@vt.edu> wrote:

On Tue, 19 Nov 2013 15:39:06 -0500, Soham Chakraborty said:

...

Vladis, I hear ya and agree to that. Problem is I have seen big and by big, I mean biggggggggg infrastructures asking for ksplice since certain sales people of certain company introduced them to the utopia that is called downtime-less-patching-and-upgrading. And obviously, if you have worked with the CLI a bit less than most of us have already had, you get the sweet inclination to go with sales and you know, voila.

Don't you just love when management makes decisions based on 8.5x11 color glossies? ;)

On Fri, 22 Nov 2013 12:21:59 +0400, Vasiliy Tolstov said:

After some time i need to update kernel. How can i deal with it with minimal downtime not using ksplice? Kexec?

The usual stock answer is "run two instances with some sort of High-Availability package between the two of them". Fail over to one instance, reboot the second, then fail over to the now-rebooted second instance and reboot the first. I've done that on SGI boxes running CXFS and NFS - the NFS client machines see only a 2-3 second pause. (The bonus is that since the two boxes do heartbeat, it also means that if one locks up or crashes, the other can seize control and continue processing without users noticing. So it's of benefit not just for updating the kernel.