Hello,

> On 14 Dec 2015, at 11:49, Fabrice Jammes <[log in to unmask]> wrote:
> 
> At JRES2015, I've seen of presentation made by Nicolas Muller and Jerome Petazzoni (a Docker core developper):     
> https://conf-ng.jres.org/2015/planning.html#article_180 
> 
> I discussed a long time with Nicolas Muller and he gave me some interesting informations: 
> 
> 1. Kernel Panic: 
>     * Nicolas confirms Docker is used on numerous production infrastructures on bare-metal cluster without problems. 
>     * Nicolas think we should upgrade to a newer kernel (Andy H. link push also in this way: https://conf-ng.jres.org/2015/planning.html#article_180) 

We already upgraded the qserv servers to the latest official kernel available for SL7 few weeks ago.

>     * Nicolas also told me that Docker work better on Debian/Ubuntu (because of the AUFS file system support) 

Debian and Ubuntu are not supported at CC-IN2P3 (as Ahmed already said).

> 
>     => Ahmed and Yvan, could we try to switch to EPEL latest kernel on IN2P3 cluster (for ccqserv125...149 first)? Can I do it by myself, or does it require some Puppet magic? 

No you can't. Moreover, as Ahmed said, by trying to install a "kernel-ml" from "elrepo", this is not supported and we could probably face some security and/or data corruption issues...

>     If this doesn't solve the "Kernel Panic" problem, then I propose to implement Ahmed proposal: 
>         i.e. put container in VM, which mount data on local block devices, so that we can restart VM by ourself. Could we please install Debian in these VM? 

The solution you proposed (container in VM) sounds a bit complicated, no? 

IMHO, the kernel panic is no more an urgent problem since an automatic reboot is triggered when it happens (kernel.panic set to 300 seconds in sysctl.conf). Of course, we need to understand those kernel panics, but it seems a bit complicated to debug :/

We could imagine to switch the Qserv cluster to CentOS 6 or 7, but this will require some efforts from our side and I wonder if this is the best thing to do... It also depends of the time constraints for you (Qserv devs). Are you ready not to use the cluster for several days if we decide to migrate to CentOS?

Yvan


---
Yvan Calas
CC-IN2P3 -- Storage Group
21 Avenue Pierre de Coubertin
CS70202
F-69627 Villeurbanne Cedex
Tel: +33 4 72 69 41 73


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