Archive for January, 2011

Creating a Red Hat Cluster: Part 2

January 3rd, 2011 No comments


Here is the second article on how to to build a Red Hat/CentOS cluster. The “Part One of this article” was posted a couple of month ago, I’m sorry for the delay but I have been a bit busy at work and at home.  I can promise that Part 3 will not take a couple of month to post. I want to terminate this series on the cluster and post some new ideas that I have.  In this article, we continue our journey on how-to build our cluster and stay tune for Part 3 coming soon.

Installing the cluster software

If you are using Red Hat, you need to register your server in order to download new software or update. You also need to subscribe to the “Clustering” and “Cluster Storage” channel in order to install these groups of software. With CentOS, this is not needed since we can download these groups of software without registration. Let’s install the clustering software, by typing this command;

# yum groupinstall Clustering

Since we will be using GFS filesystem, we will need the “Cluster Storage” software group.

# yum groupinstall “Cluster Storage”

I also found out that this package is also needed by the cluster software, so let install it.

# yum install perl-Crypt-SSLeay

If you are using a 32 bits kernel and you have more than 4 GB of memory on it, you need to install the PAE kernel and GFS modules. This will ensure that you are using all the memory available on the server.

# yum install kmod-gnbd-PAE kmod-gfs-PAE kernel-PAE

Finally, let’s make sure that you have that the servers have the latest OS update.

# yum –y update

Setting the locking type for GFS filesystem

To use the GFS (Global File System) with the cluster you need to activate the GFS locking in the /etc/lvm/lvm.conf file. We need to change the “locking_type” variable from 0 to 3, to inform LVM that we will be dealing iwth GFS volume group and GFS filesystem. This command needs to be run on all the servers.

# grep -i locking_type /etc/lvm/lvm.conf
locking_type = 0
# lvmconf --enable-cluster
# grep -i locking_type /etc/lvm/lvm.conf
locking_type = 3

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Categories: Cluster