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ID #1482

How do I replace ntpd for chrony on a Bright Cluster?

The following procedure was tested on Bright 8.2 on CentOS 7.

 

WARNING: Please note that an update of certain Bright packages can remove some of the changes that were done manually here. If the  packages node-installer or  node-installer-nfsroot are updated/reinstalled on the head node, then step 7 of this article has to be done again.

 

1 - Disable ntpd on the head node

 

Run the following commands on the head node:

 

# systemctl disable ntpd

# systemctl stop ntpd

# cmsh

% device use master

% services

% use ntpd

% stop

% set autostart no

% set monitored no

% commit

 

2 - Disable ntpd on the software images

 

Run the following commands on the head node (this has to be done for every software image)

 

# chroot /cm/images/<software images>

# systemctl disable ntpd

# exit

 

3 - Install chrony on the head node and software images

 

Run the following commands on the head node:

 

# yum install chrony

# yum install chrony --installroot=/cm/images/<software image>

… repeat this last step for every software image

 

4 - Configure chrony on the head node

 

On the head node, edit the /etc/chrony.conf file, and add the following line to it (replace the network with the network from which the compute nodes will access the head node)

 

allow 10.141.0.0/16




5 - Configure chrony on the software images

 

In every software image, edit the /etc/chrony.conf file. Within the file, comment all the lines starting with “server” and add a line which points to the IP address that the compute nodes use to reach the head node. For example:

 

server 10.141.255.254 iburst

 

6 - Configure the head node and compute nodes to manage chronyd

 

Run the following commands on the head node:

 

# cmsh

% device use master

% services

% add chronyd

% set monitored yes

% set autostart yes

% commit

% start

% category use <category of the nodes>

% services

% add chronyd

% set monitored yes

% set autostart yes

% commit

 

7 - Configure node-installer to use chrony instead of ntpd

 

Run the following commands on the head node:

 

# yumdownloader chrony libseccomp

# rpm -ivh chrony-3.2-2.el7.x86_64.rpm libseccomp-2.3.1-3.el7.x86_64.rpm --root=/cm/node-installer

 

Then configure the node-installer so the initial time synchronization will be done using chronyd. For this, edit the /cm/node-installer/linuxrc file in the head node and replace the line “timeout 10s ntpd -c /tmp/ntp.conf -q -g” with literally the following line (it automatically uses the IP address that the compute nodes use to reach the head node):

 

timeout 10 chronyd -q "server $NET_MASTER iburst"

 

8 - Reboot nodes to apply the changes

 

All the compute nodes have to be rebooted so the changes in the software images will be applied.

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