Redundancy in Windows Server 2019

Multiply that by two. This is a phrase I hear all the time when planning server deployments for work. I'm sure you have as well. Any time you are rolling out new technology, you want to plan that rollout very carefully. Figure out what servers you need, where they need to be placed, and how the networking needs to be configured for those guys. Once the planning is done, order two of everything, in case one breaks. We live in a world of always-on technology. Services going down is unacceptable, particularly if we are hosting cloud or private cloud services. Any application or service that our users depend on to get their work done is mission-critical and needs 100% uptime, or darn close to it. The problem with redundancy is that it's much easier to talk the talk than to walk the walk. Maybe one day we will be blessed with a magic Press here to make this server redundant button – but today is not that day. We need to understand the...

Network Load Balancing (NLB)

Often, when I hear people discussing redundancy on their servers, the conversation includes many instances of the word cluster, such as, "If we set up a cluster to provide redundancy for those servers..." or "Our main website is running on a cluster..." While it is great that there is some form of resiliency being used on the systems to which these conversations pertain, it is often the case that clustering is not actually involved anywhere. When we boil down the particulars of how their systems are configured, we discover that it is NLB doing this work for them. We will discuss real clustering further along in this chapter, but first I wanted to start with the more common approach to making many services redundant. NLB distributes traffic at the TCP/IP level, meaning that the server operating systems themselves are not completely aware of or relying on each other, with redundancy instead being provided at the network layer. This can...

Configuring a load-balanced website

Enough talk; it's time to set this up for ourselves and give it a try. I have two web servers running on my lab network, WEB1 and WEB2. They both use IIS to host an intranet website. My goal is to provide my users with a single DNS record for them to communicate with but have all of that traffic be split between the two servers with some real load balancing. Follow along with the steps on making this possible.

Enabling NLB

First things first, we need to make sure that WEB1 and WEB2 are prepared to do NLB, because it is not installed by default. NLB is a feature available in Windows Server 2019, and you add it just like any other role or feature, by running through the Add roles and features wizard. Add this feature on all of the servers that you want to be part of the NLB array:

Figure 12.1: Adding NLB to your servers

Enabling MAC address spoofing on VMs

Remember when we talked about unicast NLB and how the physical...

Failover clustering

We have established that NLB is a great solution for stateless applications, with a prime example being websites that you want to make highly available. What about other server roles or functions that you want to make redundant? Well, the opposite of stateless is stateful, so how about giving high availability to stateful pieces of technology?

Failover clustering provides this level of capability and can be used in cases where the nodes within the cluster are accessing shared data. This is a key factor in the way failover clustering is designed. The storage used by the cluster nodes must be shared and accessible by each node that needs it. There are many different roles and services that can take advantage of failover clustering, but there are four specific technologies that seem to make up the majority of clusters running in datacenters today: Hyper-V, file services, Exchange, and SQL. If you are working with any of these technologies – and chances...

Clustering tiers

An overhead concept to failover clustering that is important to understand is the different tiers at which clustering can benefit you. There are two levels upon which you can use clustering: you can take an either/or approach and use just one of these levels of failover clustering, or you can combine both to really impress your high-availability friends.

Application-layer clustering

Clustering at the application level typically involves installing failover clustering onto VMs. Using VMs is not a firm requirement but is the most common installation path. You can mix and match VMs with physical servers in a clustering environment, as long as each server meets the installation criteria. This application mode of clustering is useful when you have a particular service or role running within the operating system that you want to make redundant. Think of this as more of a microclustering capability, where you are really digging in and making one specific component...

Setting up a failover cluster

We are going to take a few minutes to set up a small cluster of servers so that you can see the management tools and the places that have to be visited to accomplish this. I have now backed out all of the NLB config on my WEB1 and WEB2 servers that we set up earlier so that they are just simple web servers at the moment, once again with no redundancy between them. Let's set up our first failover cluster and add both of these servers into that cluster.

Building the servers

We have two servers already running with Windows Server 2019 installed. Nothing special has been configured on these servers, but I have added the File Server role to both of them because, eventually, I will utilize these as a cluster of file servers. The key point here is that you should have the servers as identical as possible, with the roles already installed that you intend to make use of within the cluster.

One other note during the building phase: if possible...

Clustering improvements in Windows Server 2019

The clustering feature has been around for a while but is continually being improved. There have been some big changes and additions to failover clustering in the two latest LTSC releases, Server 2016 and Server 2019. Some of the changes that we will discuss were originally introduced in 2016, so they are not brand new, but are still relevant to the way that we handle clusters in Server 2019 so they are worth mentioning here.

True two-node clusters with USB witnesses

When configuring quorum for a failover cluster, prior to Server 2019, a two-node cluster required three servers, because the witness for quorum needed to reside on a witness share of some kind, usually a separate file server.

Starting in 2019, that witness can now be a simple USB drive, and it doesn't even have to be plugged into a Windows Server! There are many pieces of networking equipment (switches, routers, and so on) that can accept USB-based file storage...

Storage Replica (SR)

SR is a new way to synchronize data between servers. It is a data-replication technology that provides the ability for block-level data replication between servers, even across different physical sites. SR is a type of redundancy that we hadn't seen in a Microsoft platform prior to Windows Server 2016; in the past, we had to rely on third-party tools for this kind of capability. SR is also important to discuss on the heels of failover clustering because SR is the secret sauce that enables multi-site failover clustering to happen. When you want to host cluster nodes in multiple physical locations, you need a way to make sure that the data used by those cluster nodes is synced continuously, so that a failover is actually possible. This data flow is provided by SR.

One of the neat data points about SR is that it finally allows a single-vendor solution, that vendor being Microsoft of course, to provide the end-to-end technology and software for storage and...

Storage Spaces Direct (S2D)

S2D is a clustering technology, but I list it here separate from general failover clustering because S2D is a core component of the software-defined data center (SDDC) and has had so much focus on improvements over the past few years that it really is in a category of its own.

In a nutshell, S2D is a way to build an extremely efficient and redundant centralized, network-based storage platform entirely from Windows Server. While serving the same general purpose (file storage) as a traditional NAS or SAN device, S2D takes an entirely different approach in that it does not require specialized hardware, nor special cables or connectivity between the nodes of the S2D cluster.

To build S2D, all you need are Windows Servers; the faster, the better, but they could be normal, everyday servers. These servers must be connected through networking, but there are no special requirements here; they simply all get connected to a network, just like any other server...

Summary

Redundancy is a critical component in the way that we plan infrastructure and build servers in today's world. Windows Server 2019 has some powerful capabilities built right into it that you can utilize in your own environments, starting today! I hope that by gleaning a little more information about both NLB and failover clustering, you will be able to expand the capabilities of your organization by employing these techniques and stretching the limits of your service uptime. Even for a small-medium business, there are some great replication options in Windows Server, made possible with a limited set of servers. You could use Storage Replica to replace many other third-party options that currently exist in these environments, giving you redundant file servers in a quick-and-easy fashion. For any enterprise-class organization that hasn't tested the waters with S2D yet, what's stopping you? Let's get serious about resiliency for your Hyper-V infrastructure...

Questions

1. Which technology is more appropriate for making web server traffic redundant – Network Load Balancing or failover clustering?
2. In Network Load Balancing, what do the acronyms DIP and VIP stand for?
3. What are the three NLB modes?
4. In Windows Server 2019, is Network Load Balancing a role or a feature?
5. What roles are most often used with failover clustering?
6. What type of small device can now be used as a cluster quorum witness (this is brand new as of Server 2019)?
7. True or False—Storage Spaces Direct requires the use of SSD hard drives.