Properly designing VMware vSphere infrastructure is one of the primary keys to ensuring the vSphere environment performs correctly and is able to present a highly available infrastructure resource for business-critical virtual machines. The VMware vSphere cluster is one of the basic building blocks of vSphere as it provides an aggregated pool of ESXi server resources that allow VMware virtual machines to easily be shifted between hosts for both performance and high-availability purposes.
Table of Contents
- VMware vSphere Management Cluster Role and Benefits
- Reduced Complexity in vSphere Management
- Improved security and separation of boundaries
- Provides a boundary of resources
- Designing a Modern Management Cluster
- Final Thoughts
In the VMware vSphere ecosystem, there are different cluster types. These include management, compute, edge, and shared compute and edge clusters. These each has a specific role and intended purpose. Perhaps the one type of cluster that is often skipped when provisioning vSphere environments but one that presents a great deal of benefit in the vSphere environment is the management cluster. Often in small environments or in environments where budget may be limited, the management cluster functionality is generally multi-homed on the compute cluster.
Let’s take a look at VMware vSphere management cluster role and benefits to understand the reason why using management clusters is important and how these can be effectively designed.
VMware vSphere Management Cluster Role and Benefits
For vSphere administrators coming from small environments, management clusters are not always utilized in the environment.
Why is this less than optimal when thinking about a resilient, highly-available VMware infrastructure standpoint?
The management cluster provides resources for the management workload domain.
What does this mean?
In the software-defined data center or SDDC, the management cluster is specifically designed to run virtual machines whose primary purpose or role is in providing resources that contribute to managing or monitoring the vSphere environment or providing underlying resources for the vSphere infrastructure itself. So generally speaking, the management VMs should be deemed critical infrastructure.
Great examples of virtual machines that most likely should reside on the management cluster are vCenter Server, vSphere Update Manager, NSX Manager, NSX Controller, vRealize Operations Manager, vRealize Automation, vRealize Log Insight, vRealize Network Insight, and any other management components.
Since the management cluster is providing critical infrastructure components for the entire VMware vSphere environment, including compute and edge clusters, it is extremely important that high-availability mechanisms are put into play on the management cluster that allows it to have hardware redundancy as well as at the very least, HA running at the vSphere cluster level so that virtual machines are restarted in the event of a host failure.
Why is it important to have the “management” layer VMs separated from the production workload virtual machines?
Generally speaking, as a best practice, you don’t want to have the virtual machines that provide critical vSphere functionality running on the same infrastructure of the production workload virtual machines. Separating the management workloads provides several benefits.
These include:
- Reduced complexity in vSphere management
- Easier troubleshooting when management infrastructure separate from compute cluster
- Upgrades, patching, etc of management components provides less impact on production workloads
- Improved security and separation boundaries of management components from workload VMs
- Provides a boundary of resources
Reduced Complexity in vSphere Management
When all the VMs, both management and production workloads are located on the same cluster, you have a mix of environmental requirements. Since all the infrastructure shares the same hardware and cluster resources, all workloads must be taken into consideration when performing any type of management tasks. A wrong configuration on the vSphere cluster that multi-homes management and workload VMs will affect all VMs including management VMs. Any impact on the management VM resources can have the effect of bringing all resources down, cluster-wide.
Easier Troubleshooting
It becomes much easier to troubleshoot issues with production virtual machine workloads if you have the management virtual machines separated from the workload VMs. This allows being able to troubleshoot real performance or hardware issues with production VM workloads without at the same time, having to deal with the impact on the management VMs such as vCenter which can make troubleshooting and triaging extremely difficult. Additionally, by separating out the management VMs, they are unaffected by any runaway production virtual machines without resource restrictions that may affect all the other workloads running in the same cluster.
Upgrades and Patching of Management components has less impact on production workloads
This point is fairly intuitive, however, just to highlight this a bit further, since management components are separate from the production workloads, any maintenance performed on the management cluster and VMs in general, do not affect the running production workload VMs. At most, disruption in the accessibility of management interfaces, etc will be seen from the environment.
Improved security and separation of boundaries
There is a strong argument to the fact that if a production workload VM is compromised and is running on the same cluster as the management resources, there is a greater possibility of a security compromise of the entire vSphere infrastructure than if the management cluster components are separated from the compute cluster resources. This also helps to satisfy certain compliance and other security regulations by separating the management resources from production workloads.
Provides a boundary of resources
This point is perhaps woven into the other points already made. However, separating the management components from the workload VMs provides a boundary of resources that allows effectively limiting the “blast zone” if something bad happens in the production workload compute cluster and vice versa. Having all your management components on the compute cluster can serve to have all your “eggs in one basket” and lead to the catch 22 of having production “compute” resources down that takes everything down so that you can’t effectively manage, troubleshoot, or re-provision resources.
Designing a Modern Management Cluster
In today’s modern architecture world where software-defined technologies are driving the ability to have robust capabilities and flexibility in running workloads, running vSphere management clusters on VMware vSAN storage technology makes a lot of sense.
VMware vSAN is a very mature product at this point running production critical workloads across many different compute and management landscapes.
In many cases, the argument against having a dedicated management cluster often comes down to cost. VMware vSAN is helping organizations reduce the cost of their storage needs and this includes storage for management VMs and components.
A management cluster of (4) nodes allows having Failures to Tolerate of 1 even when taking a single host down for maintenance operations. VMware vSAN allows easily scaling up or scaling out for growing the needs of the management cluster. It allows achieving performance objectives at the VMDK or VM level and it allows communication for storage purposes to take place with traditional IP networking, so using existing switches and infrastructure is certainly a possibility.
What about running vCenter Server on vSAN, isn’t that risky?
While you interact with vSAN though vCenter Server, the data path, and all low-level activities such as object management, health, and performance monitoring are all independent from vCenter. This makes it extremely safe to run vCenter Server on top of VMware vSAN.
Final Thoughts
The VMware vSphere management cluster role and benefits provide a tremendously powerful way to isolate management VM functions from production VM workloads. The benefits include isolating resource boundaries, improving the security of the management components in the vSphere infrastructure, making it easier to troubleshoot, and less impactful on production VMs to upgrade or patch management components.
With new technologies today such as VMware vSAN powering storage, provisioning a management cluster is easier and more cost-effective than ever before. Additionally, the benefits of having a management cluster along with compute and edge clusters make it an extremely wise investment. By making full use of designing vSphere environments so they take advantage of the management cluster, organizations can effectively follow VMware best practice methodologies and designs.
This helps to ensure VMware vSphere environments are provisioned correctly, are performant, provide easy troubleshooting, and effectively allow management components to be separated from regular production workloads which offer many benefits.
Related Posts:
VMware HA and DRS Explained
Beginners’ Guide for Microsoft Hyper-V: Hyper-V High Availability – Part 25
Follow our Twitter and Facebook feeds for new releases, updates, insightful posts and more.
