This is legacy 4.4 and earlier documentation
High Availability (Active/Passive) sipXecs implementation using existing iSCSI shared storage and CentOS clustering.
- It should be noted this is a highly complex topic.
- This document does not cover all aspects of clustering and failover scenarios and is not intended to go through the exact installation steps.
- It is advisable to keep the cluster nodes on their own subnet as each node broadcasts "heartbeats" to the other node to ensure it is still alive.
- Two high power servers (8 GB RAM minimum) with three NICs in each
- Dedicated networks for each service
- Fencing device on each server such as Dell DRAC or HP iLO. This is so if a cluster node is misbehaving it is immediately powered off instead of causing data corruption as well as to trigger proper failover.
The following is a diagram of the clustering scenario we will be setting up:
Install CentOS 5.6 on two identical servers. You may also configure the NICs at this point. One NIC will be for the iSCSI storage network (eth2), one will be for clustering heartbeat (eth1), and one NIC will be for all other communications, including sipXecs (eth0).
When setting the default gateway, it must be set on the main communication interface (eth0). This is done automatically in initial setup but can be changed to the detriment of the system post install. DO NOT set the default gateway on any interface other than the primary communication interface (eth0).
It is also advisable to set the hostname at this time. The hostname MUST be the same on both systems otherwise sipXecs will fail to function if switched to another node.
When prompted for software selection, deselect desktop – Gnome and select Clustering and Storage Clustering. Perform the install.
After each system reboots you'll need to disable the firewall and turn of SELinux. This is done when the Setup Agent appears. Choose Firewall, then disable all security settings.
After you have disabled the security settings perform a system update on both systems:
After the update reboot both systems. Once you've rebooted, install the software package xauth to enable X11 forwarding (used later):
Connect to Shared iSCSI disk
Each server needs to have iSCSI turned on to connect. Run the following commands to enable iSCSI:
On each server you need to connect to a blank (fresh) shared iSCSI disk. For example, if your iSCSI shared disk is located at IP address 172.16.5.10 you would run the following command on each server:
You will now see the addition of a drive to the server, usually /dev/sda or something similar.
Configure LVM to allow for filesystem clustering
Edit /etc/lvm/lvm.conf on each node and change the following line:
and run the following command for this change to take effect:
Add Clustered Network Script
Create a file on both nodes called /usr/local/bin/clusnet and fill it will the following, modifying SIPX_IP='172.16.1.5' on line 15 to the be the IP address of the sipXecs system, as well as the Ethernet interfaces for your services:
You'll also need to make the script executable by running:
This script replaces your primary communication network's IP address with that of the sipXecs servers IP address. This is so there will not be any IP address conflict within sipXecs services.
Initial cluster configuration is done with the utility system-configure-cluster which, if you're running a headless (text only) install, will require the use of X forwarding via PuTTY and Xming. Download Xming from http://sourceforge.net/projects/xming/files/Xming/220.127.116.11/Xming-6-9-0-31-setup.exe/download and install it, then start it. In PuTTY, enable the option Enable X11 Forwarding under Connection >> SSH >> X11. You may then connect to the primary node server and run the following command:
This will open the CentOS cluster configuration system:
Click on Create New Configuration to begin configuring the cluster.
Enter the name of the cluster you wish to create. For this example we will create a cluster called uc_cluster:
For a simple two node cluster it is not necessary to use a quorum disk. Click OK.
We now need to add all of our cluster information into the cluster configuration manager the first thing we need to do is add our cluster nodes. To do this click on Cluster Nodes and click Add a Cluster Node. Be sure to use IP addresses and not DNS host names :
Click OK then add the second node in the same fashion.
Add Fencing Device
In the system requirements section of this document it was noted that you would need some sort of manual fencing device to enable the cluster to power down a troublesome node. To add a fencing device, click on Fence Devices then click on Add a Fencing Device. You will now need to select the type of fencing device you have installed:
Once you have selected your fencing device you will need to enter a descriptive name, IP address, username, and password to connect to the device.
Add one fencing device into the cluster manager for each iLO/DRAC you have (for two servers, you'd have two fencing devices).
Fencing, however, is beyond the scope of this document. For demonstration purposes we will use manual fencing.
Add Fencing Device to Cluster Nodes
Each cluster node needs to have its own fencing device assigned to itself so that the cluster manager knows how to power down the device. To add a fencing device to a cluster node, click on Cluster Nodes, click on the cluster node you wish to modify, then click Manage Fencing For This Node. You will now see the following:
Click on Add a New Fence Level then click on the fence level that was just created, Fence-Level-1 then click Add a New Fence to this Level, then select the fence device associated with that server. Click OK to return to the cluster node fence configuration:
Click Close to return to the cluster configuration system. Repeat the cluster node fence configuration for the other node in this cluster.
All items utilized by the cluster nodes are known as resources. In our case, our resources are:
- Network device startup script
- IP Address
- PostgreSQL script
- Phonelogd script
- sipXecs script
When using a script in a clustering environment in must be an init style script, accepting stop, start, restart, and status as arguments.
To add an IP address click Create a Resource then in the resource type selection drop down box select IP Address. Enter the IP address that sipXecs will be using along with the subnet mask, then click OK.
To add a PostgreSQL script click Create a Resource then in the resource type selection drop down box select Script. Enter the following information:
- Name: PGSQL-8
- File (with path): /etc/init.d/postgresql
Now you'll need to add a script for network device startup, phonelogd and sipxecs. To add a script click Create a Resource then in the resource type selection drop down box select Script. For sipxecs, enter the following information:
- Name: sipXecs
- File (with path): /etc/init.d/sipxecs
For phonelogd, enter the following information
- Name: Phonelogd
- File (with path): /etc/init.d/phonelogd
For the network device startup script enter the following information
- Name: clusnet
- File (with path): /usr/local/bin/clusnet
Add Cluster Service
Once you've created all the necessary resources you must now assign them to a cluster service.
To add a service, click on Services then click Add a Service. Enter a descriptive name for the service, such as sipXpbx, then click OK. The service configuration window will now appear:
You'll notice there are two options regarding resources: Create a new resource for this service and Add a Shared Resource to this service. Since we already created the resources we do not need to create them again, so click Add a Shared Resource to this service which will prompt you to select an existing resource:
You first need to select the IP Address that you created earlier and click OK. This will be the top resource in this service, meaning this resource will start before all other resources start.
Once you've added the the IP address you will need to add the network device startup script (clusnet) by clicking Add Shared resource to this service. Select the clusnet resource created earlier then click OK. Select the clusnet resource you just added then click Attach a Shared Resource to the selection, then select the PGSQL-8 resource you created earlier and click OK. Now add Phonelogd and sipXecs the same way as subordinates of the PostgreSQL resource.
Your resource hierarchy should look similar to this:
For now we don't want this service to automatically start when the cluster service starts so we need to disable automatic startup for this service. To do this uncheck the Autostart This Service checkbox, then click Close
Save cluster configuration
To save the cluster configuration, click on File then click on Save and save the configuration to /etc/cluster/cluster.conf
Propagate the Cluster Configuration
For the initial propagation of the cluster configuration to the second cluster node you will need to manually copy /etc/cluster/cluster.conf from the primary node to the secondary node. This can be done with SCP or by copying and pasting the contents of the file.
Start Clustering Service
To start the clustering service and all of the necessary dependencies, run the following commands on both nodes:
To verify that the cluster service is up and running, run the clustat command. You should see output similar to the following:
Create Clustered Storage
As of this writing the best filesystem to use for cluster storage is GFS. This is because unlike most other filesystems, GFS is safe to mount on both nodes at the same time without risking data corruption. This allows for quick failover with less risk of data corruption.
GFS requires LVM to operate properly, so we will need to create a LVM physical volume (PV), volume group (VG), and logical volumes (LV). This only needs to be done on one node of the cluster, preferably the primary node.
Enter the following commands to create the PV and the VG (assuming /dev/sda for the shared disk)
Now let's create some logical volumes. There will need to be 5 total logical volumes as there are 5 distinct area that need to be shared for proper sipXecs operation:
We'll start off with a logical volume called etc_sipxpbx:
This creates a 5 GB logical volume with the name etc_sipxpbx in the volume group sipx-vol.
Now we need to create the rest of these volumes. Bear in mind that the PostgreSQL database (/var/lib/pgsql) and the sipXecs data store (/var/sipxdata) will need the most space.
Run the following commands, changing the space values per your needs:
Create GFS file systems
Run the following command to create a GFS partition on the etc_sipxpbx volume (this only needs to be done on one node of the cluster, preferably the primary node):
Here is an explanation of the arguments:
- -p lock_dlm
- This defines the locking method.
- -t uc_cluster:etc_sipxpbx
- This defines the lock table to be used. The first part is the cluster that will be utilizing it (uc_cluster) and the second part can be anything but it is easiest to use the LV name.
- -j 2
- This defines the number of journals to use. The number of journals is directly coordinated to the number of nodes in your cluster.
- This is the LVM device we wish to create the filesystem on
Create the filesystem on each LV:
Mount Filesystems in Appropriate Locations
First we need to create the directories where these filesystems will be located. Run the following commands on both nodes:
Edit /etc/fstab and add the following lines to the end of the file:
Now mount all of the partitions on both servers:
Install sipXecs Packages
Now that we have all the shared storage mounted we can install and set up sipXecs. First we need to install the repository. Edit /etc/yum.repos.d/sipxecs.repo on both nodes and add the following information:
Now, on the first node only, install the necessary packages to support sipXecs:
After the first installation has completely finished, perform the same installation on the second node.
In the unlikely event that your postgres and sipxchange UID and GID do not match up on the two nodes, you will need to change /etc/passwd and /etc/group on the first node to match the values present on the second node. This is because the installation is performed last on the second node and filesystem permissions are set to the UID of the user on the second node.
Run sipXecs setup
On the primary node, enable the sipXecs NIC buy running the following command:
Now modify /etc/hosts on both nodes to have the correct information. This includes setting the local hostname to the cluster IP address:
Run the following command on the primary node:
Enter all the necessary information and then when prompted, select Exit to prompt.
Disable sipXecs services from starting at bootup:
Now we need to generate the default postgres configuration. On the primary server start postgresql:
And now stop it (the cluster will manage this service):
You'll also need to change the IP address of your primary node's communication interface (eth0) back to the original settings by running:
DNS Caching Nameserver Configuration
Because running sipxecs-setup-system would have broken many things we'll have to perform a few steps involving DNS manually.
The first thing we need to do on both nodes is remove the file /etc/named. caching-nameserver.conf and add our own /etc/named.conf with the following contents:
Change the forwarders section to match your DNS servers.
Restart the caching DNS server and enable it during startup:
Modify /etc/resolv.conf to use the local caching DNS server first, changing the other values as needed:
Reboot both nodes simultaneously for all configuration changes to take effect.
Starting sipXecs Cluster Service
To start sipXecs you'll need to start system-config-cluster then click on the Cluster Management tab at the top of the window. Here you'll see the active nodes and services:
To start the sipXpbx service, click on the service and then click the Enable button. This will start all the necessary services.