This blog contains my day to day works esp the knowledge that i gain.: July 2013

How to build a simple Linux cluster.(tried to make a drop out of an ocean).

Things that you require before starting to build the cluster with one Virtual node and storage fail-over from one node to the other.

1) SUSE 11 Package DVD with High Availability Package.
2) Two Virtual \ Physical machines on which SUSE package can be installed.
3) Three Static IP addresses that could be used.
4) ISCSI storage.
5) Understand Linux network configuration specific to multicast and broadcast.
why to understand this ?
we Need to configure the network and cluster network configuration which is important for cluster communication. very important is to know which multicast ip address could be used in your network.
http://en.wikipedia.org/wiki/Multicast
http://en.wikipedia.org/wiki/Multicast_address
6) Understand the resource management of the cluster with peacemaker.
http://lcmc.sourceforge.net/1.1-lcmc/pdf/Clusters_from_Scratch/Pacemaker-1.1-Clusters_from_Scratch-en-US.pdf
7) Understand how password less communication could be achieved between two Linux machines for SSH communication.
http://www.linuxproblem.org/art_9.html
8) Have a list of packages that needs to be installed for your requirement.
in the present use case following packages are being installed.

a) Openais
b) ocfs2 (including the file system package).
https://oss.oracle.com/projects/ocfs2/dist/documentation/v1.4/ocfs2-1_4-usersguide.pdf
c) o2cb
d) corosync
e) iscsi initiator
f) pacemaker.
g) heartbeat
h) crm
i) hawk

9) Last but not the least it helps to read the complete documentation from the following link before you start the step by step process for creating a basic cluster.

https://www.suse.com/documentation/sle_ha/singlehtml/book_sleha/book_sleha.html

Step By Step:

1) Install the OS with the all the above mentioned packages on a virtual machine or a physical machine.
2) Configure the machine name (host-name) and static IP of the machine.
3) make sure that the communication between both the machines with the IP and the host name is resolvable.
Good to configure the Machine Name and IP in the DNS properly. The other way is to have the host and the IP address configured in the hosts file on each of these machines \ nodes.
4) configure the ISCSI storage on the machine in such a way that the same storage is shared across both the machines and is visible to both of them with permissions to read and write for both the machines.
http://www.linuxtopia.org/online_books/suse_linux_guides/SLES10/suse_enterprise_linux_server_installation_admin/sec_inst_system_iscsi_initiator.html

5) Configure the password for the High availability user group that is used to login into the peacemaker

To log in to the cluster from the Pacemaker GUI, the respective user must be a member of the haclientgroup. The installation creates a linux user named hacluster and adds the user to the haclient group.

Before using the Pacemaker GUI, either set a password for the hacluster user or create a new user which is member of the haclient group.

Do this on every node you will connect to with the Pacemaker GUI.
6) Configure the initial cluster configuration as specified in the steps below with or without any redundancy in the network configuration.
https://www.suse.com/documentation/sle_ha/singlehtml/book_sleha/book_sleha.html#sec.ha.installation.setup.manual.

the above step completes the configuration of your cluster without any storage.

you can check this with crm_mon command which gives you the details of the configured nodes and resources with the configuration information.

7) Now once the above steps are done we are done with the cluster node configuration we need to look into the resource configuration. (you need to understand which combination of resource works for you.). for me i have considered the disk and Virtual ip as the resource for the cluster and i am configuring them as part of group which make it more easy for the group to be moved from one node to the another in case of a fail-over.

8) configure the file system once the above stuff is done. make sure that the ISCSI storage is available for both the nodes. Format is with ocfs2 file system. once the file system is configured.the perform the below step. once the file system is configured. on the ocfs2console configure the cluster nodes. configure oc2b and ocfs2 to start at the boot time on both the nodes.

configure o2cb with the following command on both nodes.

/etc/init.d/o2cb configure

dont forget to provide the cluster name in the above configuration. its a must.

9) open the crm_gui from the node on which the cluster configuration is being configured and select the resource node and the select the add option. select the group radio button and give a name to the group then configure the primitive ip address and primitive storage group configuration.

ip : ocf::heartbeat::IPaddr2
need to specify the ipaddress and netmast for this to work properly.

storage : ocf::heartbeat::Filesystem
need to specify the block device that is formatted and available on both the nodes.
need to specify the mount path on the local machine.
need to speficy the file system parameter correctly for this.

once again last but not the least there are things that are still confusing \ not understood. you can send me an email to get answers for things that are not clear. I could append the same in this blog.

This blog contains my day to day works esp the knowledge that i gain.

Tuesday, July 30, 2013

Install Bash on AIX 7.1

Wednesday, July 24, 2013

Simple Linux Cluster.