MCSA Windows Server 2012 R2 Configuring Advanced Services Study Guide: Exam 70-412

Chapter 1

Configure and Manage High Availability

THE FOLLOWING 70-412 EXAM OBJECTIVES ARE COVERED IN THIS CHAPTER:

Configure Network Load Balancing (NLB)

This objective may include, but is not limited to:

Install NLB nodes

Configure NLB prerequisites

Configure affinity

Configure port rules

Configure cluster operation mode

Upgrade an NLB cluster

Configure failover clustering

This objective may include, but is not limited to:

Configure Quorum

Configure cluster networking

Restore single node or cluster configuration

Configure cluster storage

Implement cluster aware updating

Upgrade a cluster

Manage failover-clustering roles

This objective may include, but is not limited to:

Configure role-specific settings including continuously available shares

Configure VM monitoring

Configure failover and preference settings

Manage Virtual Machine (VM) Movement

This objective may include, but is not limited to:

Configure Virtual Machine network health protection

Configure drain on shutdown

Perform quick, live and storage migrations

Import/export/copy of VMS

The R2 update to Windows Server 2012 has improved upon the rich high availability capabilities already present in Windows Server 2012. The management, reporting, and ease of use of the feature set are all worth mentioning, but the expansion of features is the greatest benefit of the R2 update with regard to high availability.

The exam will cover the new features at a high level, and it will cover the basic configuration and operational functions for both a failover cluster and a network load balancer. This chapter will introduce how to achieve high availability with hardware and operational changes as well as how to use the high availability features of Windows Server 2012 R2.

Any discussion of high availability, network load balancers, and clustering would not be complete without a discussion of high availability in general. The chapter will first cover what it means, both from a purely technical perspective and from a business perspective.

Components of High Availability

High availability is a buzzword that many application and hardware vendors like to throw around to get you to purchase their products. Many different options are available to achieve high availability, and there also seems to be a number of definitions and variations that help vendors sell their products as high-availability solutions.

When it comes right down to it, however, high availability simply means providing services with maximum uptime by avoiding unplanned downtime. Often, disaster recovery (DR) is also closely lumped into discussions of high availability, but DR encompasses the business and technical processes that are used to recover once a disaster has happened.

Defining a high availability plan usually starts with a service level agreement (SLA). At its most basic, an SLA defines the services and metrics that must be met for the availability and performance of an application or service. Often, an SLA is created for an IT department or service provider to deliver a specific level of service. An example of this might be an SLA for a Microsoft Exchange server. The SLA for an Exchange server might have uptime metrics on how much time during the month the mailboxes need to be available to end users, or it might define performance metrics for the amount of time it takes for email messages to be delivered.

When determining what goes into an SLA, two other factors need to be considered. However, you will often see them discussed only in the context of disaster recovery, even though they are important for designing a highly available solution. These factors are the recovery point objective (RPO) and the recovery time objective (RTO).

An RTO is the length of time an application can be unavailable before service must be restored to meet the SLA. For example, a single component failure would have an RTO of less than five minutes, and a full-site failure might have an RTO of three hours. An RPO is essentially the amount of data that must be restored in the event of a failure. For example, in a single server or component failure, the RPO would be 0, but in a site failure, the RPO might allow for up to 20 minutes of lost data.

SLAs, on the other hand, are usually expressed in percentages of the time the application is available. These percentages are also often referred to by the number of nines the percentage includes, as shown in Table 1.1.

Table 1.1 Availability percentages

Two important factors that affect an SLA are the mean time between failure (MTBF) and the mean time to recovery (MTTR). To be able to reduce the amount of unplanned downtime, the time between failures must be increased, and the time it takes to recover must be reduced. Modifying these two factors will be addressed in the next several sections of this chapter.

Achieving High Availability

Windows Server 2012 R2 is the most secure and reliable Windows version to date. It also is the most stable, mature, and capable of any version of Windows. Although similar claims have been made for previous versions of Windows Server, you can rest assured that Windows Server 2012 R2 is much better than previous versions for a variety of reasons.

An honest look at the feature set and real-world use should prove that this latest version of Windows provides the most suitable foundation for creating a highly available solution. However, more than just good software is needed to be able to offer high availability for applications.

High Availability Foundation

Just as a house needs a good foundation, a highly available Windows server needs a stable and reliable hardware platform on which to run. Although Windows Server 2012 R2 will technically run on desktop-class hardware, high availability is more easily achieved with server-class hardware. What differentiates desktop-class from server-class hardware? Server-class hardware has more management and monitoring features built into it so that the health of the hardware is capable of being monitored and maintained.

Another large difference is that server-class hardware has redundancy options. Server-class hardware often has options to protect from drive failures, such as RAID controllers, and to protect against power supply failures, such as multiple power supplies. Enterprise-class servers have even more protection.

More needs to be done than just installing Windows Server 2012 R2 to ensure that the applications remain running with the best availability possible. Just as a house needs maintenance and upkeep to keep the structure in proper repair, so too does a server. In the case of a highly available server, this means patch