Maintenance script: Created page with " === Short description of the reboot script === Now, on the workernodes, there is a cron script, written in Perl, that checks if a reboot is needed and if if all the conditio..."

2015-08-26T12:28:51Z

Created page with " === Short description of the reboot script === Now, on the workernodes, there is a cron script, written in Perl, that checks if a reboot is needed and if if all the conditio..."

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=== Short description of the reboot script ===
Now, on the workernodes, there is a cron script, written in Perl, that checks if a reboot is needed and if if all the conditions are met in order to reboot safely. Here is the checklist done by the script :
*node must be offline;
*kernel release in "uname -r" is different from default kernel in /etc/grub.conf;
*node must be drained.
If all these conditions are fullfilled, then a "reboot" command is issued.
=== The new recipe to update kernel on the workernodes ===
Normally, in CB9, the kernel update should be done automatically by SPMA-YUM through the usual method of update of repositories. And so, it should not be necessary to specify explicitly a kernel release in the templates. However, due to a bug in the component ncm-grub (versions 14.2 to 14.5), we are in fact obliged to do so, by setting the variable KERNEL_VERSION_NUM in site/global_variables. (Note that it is in fact a nasty trick : it only works because all the machines in CB9 are in SL63.)

In brief, here is the recipe :
#Update the errata repository for SL.
2. Check in the updated repo what is the new kernel release and report the value in KERNEL_VERSION_NUM.
3. Adapt the nlist REPO_YUM_SNAPSHOT_DATE in site/global_variables.
4. Commit and runcheck.
5. Put offline the nodes you want to update.
6. Wait...

=== Software environment of the reboot script ===
The reboot script is deployed through Quattor, thanks to the template :
<pre>
config/reboot_wn
</pre>
For the script to work, the cream server must publish a list of offline workernodes on a webserver. This is done through the template :
<pre>
config/cream_clusterinfo
</pre>
If you look at the code of this template, you will see that the list of offine workernodes is copied to the webserver like this :
<pre>
scp offline_wns.txt quatcli:/var/www/html/clusterinfo/
</pre>
So, make sure that the public ssh key of cream is in the .ssh/authorized_keys of quatcli, and do at least on ssh from cream server to the webserver to add the webserver the know_hosts file.

As you don't want the whole web to access your webserver, you may want to secure it a bit by adding something like this at the end of the httpd.conf :
<pre>
<Location /clusterinfo/>
Order deny,allow
Deny from all
Allow from wn.iihe.ac.be
Allow from iihe.ac.be
</Location>
</pre>

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NewMethodUpdateKernelWorkernodes - Revision history

Maintenance script: Created page with " === Short description of the reboot script === Now, on the workernodes, there is a cron script, written in Perl, that checks if a reboot is needed and if if all the conditio..."