This IBM® Redbooks Solution Guide describes how to use the strategies and the capabilities of IBM PureApplication® System to provide system high availability (HA) and disaster recovery (DR).

The goal of any enterprise is to operate systems uninterrupted for a long time and to reconstruct a data center’s operations in the event of disaster.

This IBM® Redbooks® publication Solution Guide describes how to use the strategies and the capabilities of IBM PureApplication® System to provide system high availability (HA) and disaster recovery (DR). PureApplication System provides a high availability framework to eliminate single points of failure. PureApplication System also provides technologies to aid in designing disaster recovery scenarios. Figure 1 shows a simple disaster recovery strategy.


Figure 1 - Simple DR strategy


Did you know?

System administration teams need solid tools and processes to provide system HA and system DR. IBM PureApplication System provides the technology to designhigh availability solutions and disaster recovery scenarios.


Business value

PureApplication System provides a flexible platform for running a wide range of application workloads in a cloud infrastructure. Its design helps to eliminate single points of failure with the goal of allowing applications that are running in the rack to achieve high levels of availability. Businesses that strive for high levels of resiliency must consider how to run workloads across multiple systems and even across geographically distributed data centers. This strategy alleviates problems by resolving them proactively outside of any single piece of hardware, a local network, or power supply. Therefore, a failure of network or equipment does not result in a potentially lengthy outage for that service.


Solution overview

The HADR solutions provided by PureApplication System are described as HADR scenarios in Implementing High Availability and Disaster Recovery in IBM PureApplication Systems V2, SG24-8246. The HADR scenarios describe how to build HADR solutions using a combination of patterns and HADR capabilities (both hardware and software) built into the PureApplication System.


Solution architecture: PureApplication System hardware HA

PureApplication System’s hardware redundancy is designed for HA. Compute nodes, network controllers, management nodes, virtualization nodes, storage controllers, and storage are all redundant and contribute to a highly available environment (Figure 2).


Figure 2 - PureApplication System, HA through hardware redundancy (W2500-384)


The following list notes the component level details available on a single rack system:

• Compute nodes: The management system automatically routes around failed cores. If an entire node fails, the system tries to move the VM to another compute node in its cloud group (if free space is available).

• Network controllers: Cabling and switches are redundant. The failure of one of the controllers will reduce bandwidth. Service is continuous.


• Management nodes: Node has a backup server. A floating IP address is assigned to the active management node (workload deployer).


• Virtualization nodes: Node has a backup server.


• Storage controllers: Each controller has two canisters that service all of the traffic. If one fails, the other handles all traffic.

• Storage: SSD and HDD storage is configured in RAID5 plus spares. Storage is designed to tolerate two concurrent failures without data loss (after the spares are in use).

• Storage volumes are additional storage that can be attached to virtual machines. For example, adding storage volumes for DB2® to host large databases.

• Block storage is a new type of storage volume that was introduced with PureApplication System V2.0. Block storage is declared with the storage area network (SAN) found in the PureApplication System. Data is stored in volumes, which are also referred to as blocks. Block storage allows administrators to create volumes, of type block, that allow better access to the underlying SAN. Block storage provides access to multiple blocks through the file system.


• Configure block storage replication for disaster recovery at the individual storage volume level instead of replicating the entire system configuration for disaster recovery. Replication for each storage volume can be configured between local and remote (recovery) systems in either direction. Replication is configured in volume replication pairs.


• Configure external storage to one or more PureApplication System racks. To do so, make a connection from an external storage volume controller to the PureApplication System rack’s SAN connection. External storage volumes can then be assigned to cloud groups as either block or block shared storage volume types.

• DB2 10.5 Virtual System Pattern: This pattern includes the HADR feature that provides a high availability solution for both partial and complete site failures. This pattern supports up to three remote standby servers.


• WebSphere® Application Server patterns: These patterns compose cell configurations with deployment managers, custom nodes, web servers, and built-in script packages.


• WebSphere MQ: There are several HADR options possible with WebSphere MQ (such as MQ Clustering and Multi-Queue Instance Manager (MQM) using GPFS™ as the mechanism to share the file system across the different WebSphere MQ instances).


• Load balancers such as the WebSphere Application Server On Demand Router and DataPower® XI52 Virtual Appliance.

• IBM Pattern for GPFS: The IBM Pattern for GPFS can be deployed as a GPFS cluster. The GPFS cluster provides high-performance, highly available storage to the middleware and applications that are deployed in the IBM PureApplication System environment. GPFS allows the same file to be accessed from multiple different clients. GPFS is built to be redundant so that the file system remains active even if the host nodes fail.

• Replicate management data: These data include workload components such as patterns, virtual images, pattern types, script packages, and plug-ins. These data can be synchronized automatically through the multi-target deployment features of PureApplication System V2.0.


• Replicate application data: These data include logs, message queues, configuration data, and databases.


• Redirect network traffic: Traffic from the primary system to the backup system.

• WebSphere Application Server V8.5.5, see Table 1.

• DB2 V10.5, see Table 2.

• WebSphere MQ V7.5 (Hypervisor Image), see Table 3.

• WebSphere Application Server and DB2, see Table 4.

• “Solution architecture: PureApplication System hardware HA” on page 3

• “Solution architecture: PureApplication System capabilities” on page 4


• “Solution architecture: PureApplication System patterns” on page 4

• “Solution architecture: PureApplication System DR” on page 5

• IBM PureApplication System product page

http://www.ibm.com/ibm/puresystems/us/en/pf_pureapplication.html

• A tour of the hardware in IBM PureApplication System: The second generation

http://www.ibm.com/developerworks/websphere/techjournal/1407_woolf2/1407_woolf2.html

• Achieving business continuity in IBM PureApplication System

http://www.ibm.com/developerworks/websphere/techjournal/1309_brown1/1309_brown1.html

• Achieving high availability across multiple sites using IBM PureApplication System

http://www.ibm.com/developerworks/cloud/library/cl-ps-aim1305-hadrmultisites/index.html

• IBM Offering Information page (to search on announcement letters, sales manuals, or both)

http://www.ibm.com/common/ssi/index.wss?request_locale=en

• PureSystems® Centre:

http://www.ibm.com/ibm/puresystems/us/en/puresystemscentre.html