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In the following, learn about the system requirements and which preparations to take before installing the High Availability Extension. Find a short overview of the basic steps to install and set up a cluster.
The following list specifies hardware requirements for a cluster based on SUSE® Linux Enterprise High Availability Extension. These requirements represent the minimum hardware configuration. Additional hardware might be necessary, depending on how you intend to use your cluster.
1 to 16 Linux servers with software as specified in Section 2.2, “Software Requirements”. The servers do not require identical hardware (memory, disk space, etc.).
At least two TCP/IP communication media. Cluster nodes use multicast for communication so the network equipment must support multicasting. The communication media should support a data rate of 100 Mbit/s or higher. Preferably, the Ethernet channels should be bonded.
Optional: A shared disk subsystem connected to all servers in the cluster from where it needs to be accessed.
A STONITH mechanism. STONITH is an acronym for “Shoot the other node in the head”. A STONITH device is a power switch which the cluster uses to reset nodes that are thought to be dead or behaving in a strange manner. Resetting non-heartbeating nodes is the only reliable way to ensure that no data corruption is performed by nodes that hang and only appear to be dead.
For more information, refer to Chapter 9, Fencing and STONITH.
Ensure that the following software requirements are met:
SUSE® Linux Enterprise Server 11 SP1 with all available online updates installed on all nodes that will be part of the cluster.
SUSE Linux Enterprise High Availability Extension 11 SP1 including all available online updates installed on all nodes that will be part of the cluster.
A shared disk system (Storage Area Network, or SAN) is recommended for your cluster if you want data to be highly available. If a shared disk subsystem is used, ensure the following:
The shared disk system is properly set up and functional according to the manufacturer’s instructions.
The disks contained in the shared disk system should be configured to use mirroring or RAID to add fault tolerance to the shared disk system. Hardware-based RAID is recommended. Host-based software RAID is not supported for all configurations.
If you are using iSCSI for shared disk system access, ensure that you have properly configured iSCSI initiators and targets.
When using DRBD to implement a mirroring RAID system that distributes data across two machines, make sure to only access the replicated device. Use the same (bonded) NICs that the rest of the cluster uses to leverage the redundancy provided there.
Prior to installation of the High Availability Extension, execute the following preparatory steps:
Configure hostname resolution and use static host information by
editing the /etc/hosts file on each server in the
cluster. For more information, see the SUSE Linux Enterprise Server
Administration Guide, available at
http://www.novell.com/documentation. Refer to
chapter Basic Networking > Configuring Hostname and
DNS.
It is essential that members of the cluster are able to find each other by name. If the names are not available, internal cluster communication will fail.
Configure time synchronization by making cluster nodes synchronize to a time server outside the cluster. For more information, see the SUSE Linux Enterprise Server Administration Guide, available at http://www.novell.com/documentation. Refer to chapter Time Synchronization with NTP.
The cluster nodes will use the time server as their time synchronization source.
After the preparations are done, the following basic steps are necessary to install and set up a cluster with SUSE® Linux Enterprise High Availability Extension:
Installation of SUSE® Linux Enterprise Server and SUSE® Linux Enterprise High Availability Extension as add-on on top of SUSE Linux Enterprise Server. For detailed information, see Section 3.1, “Installing the High Availability Extension”.
Configuring global cluster options and adding cluster resources.
Both can be done either with a graphical user interface (GUI) or with command line tools. For detailed information, see Chapter 5, Configuring and Managing Cluster Resources (GUI) or Chapter 6, Configuring and Managing Cluster Resources (Command Line).
To protect your data from possible corruption by means of fencing and STONITH, make sure to configure STONITH devices as resources. For detailed information, see Chapter 9, Fencing and STONITH.
Depending on your requirements, you may also want to configure the following file system and storage-related components for your cluster:
Create file systems on a shared disk (Storage Area Network, SAN). If necessary, configure those file systems as cluster resources.
If you need cluster-aware file systems, use OCFS2.
To allow the cluster to manage shared storage with Logical Volume Manager, use cLVM, which is a set of clustering extensions to LVM.
To protect your data integrity, implement storage protection by using fencing mechanisms and by ensuring exclusive storage access.
If needed, make use of data replication with DRBD.
For detailed information, see Part III, “Storage and Data Replication”.