Today, the software-defined data center is truly taking over the landscape of infrastructure in the enterprise. The areas of compute, networking, and storage have been effectively abstracted away from the underlying physical hardware. In fact, most organizations today who are looking at hardware refreshes of existing infrastructure are typically looking at software-defined approaches to replacing the traditional discrete hardware layer.
For many organizations, virtualization has already become a mainstay in the infrastructure landscape, effectively allowing the compute layer to be virtualized over the past several years. Networking has followed suite which such products as VMware’s NSX and others that have allowed abstracting the network away from the physical networking hardware. Storage is no different. VMware vSAN has become the industry leader in software-defined storage architecture.
With customer numbers growing steadily, vSAN has certainly taken hold in the industry. VMware vSAN provides a powerful, stable, and performant storage foundation on which to run production workloads. The popularity and rapid adoption of the solution have been a result of the ease of which vSAN can be implemented and the management visibility into the software-defined environment. This takes place in the same management tool, the VMware vSphere client, that customers are already familiar with in managing VMware vSphere environments. This allows effective troubleshooting and other triaging of potential issues.
In this post, we will take a look at Monitoring VMware vSAN effectively to see how vSAN environments can be monitored and how to quickly find problem areas when they arise using in the box tools found in the vSphere client.
Common VMware vSAN Problem Areas
Despite the nature of software-defined infrastructure being driven at the software layer, the hardware is still an extremely important consideration! Most know and have experienced the issues that result in virtualized environments when hardware issues arise. Software-defined technologies, however, provide a great way to be “unlocked” from the specific hardware that may have issues and allow shifting workloads from unhealthy hardware over to healthy nodes. However, there is usually some type of impact that is seen either initially, or as the extra load imposed by losing resources is realized.
When looking at monitoring VMware vSAN, there are typically two areas of the infrastructure that can lead to VMware vSAN problems – the vSAN network and using hardware that is not compatible or not on the VMware Virtual SAN Compatibility Guide.
Let’s look at each of these areas to see how problems typically present themselves and how they can be avoided.
VMware vSAN Network Issues
An absolute prerequisite to having a stable, functioning, and performant VMware vSAN environment is a properly configured and architected VMware vSAN network. The VMware vSAN network is required to allow vSAN to properly communicate between the nodes in the VMware vSAN environment. When the network is designed and configured, there are many aspects that need to be properly configured to ensure the vSAN communication takes place correctly and without issue. Storage networks in general require more attention to detail than a simple client/server network that only needs simple IP connectivity. Storage networks typically reveal flaws in the design much more quickly than other kinds of networks since storage communication generally stresses the underlying infrastructure to a much higher degree than other types of IP communication. Storage traffic is generally more intensive from a bandwidth, latency, and configuration standpoint than other types of traffic.
Many network issues may revolve around inconsistent configurations between the different vSAN nodes in the vSAN cluster. The VMware vSAN cluster requires consistent configuration between all nodes so that proper configuration network settings can be implemented across the cluster. Having misconfigured or inconsistent network configurations can lead to performance, stability, and other issues. Thankfully, the latest versions of VMware vSAN do a great job of highlighting some of the more common network configuration issues such as improperly configured or inconsistently configured MTU values,
Another area in the configuration that leads to issues is the compatibility of the hardware components found in the vSAN node with the VMware Compatibility Guide or HCL. It is imperative that customers use only hardware and components that are found on the VMware Compatibility Guide. Supported compatibility goes as far as even the drivers and firmware that are used with supported hardware.
Make sure to verify the information on the VMware Compatibility Guide – https://www.vmware.com/resources/compatibility/search.php for all the vSAN nodes in the cluster.
Another issue results from a support standpoint when hardware, components, drivers, or firmware are used that are not found on the VMware Compatibility Guide. You place yourself in a position where VMware support may be limited in what they can do if issues do occur if they can even help at all.
Using only the hardware found in this HCL is beneficial from many different aspects. However, keep in mind, the compatibility guide saves customers a tremendous amount of time and effort trying to validate if the hardware is supported or not. The hardware found on the HCL has already been thoroughly tested and should perform adequately and without issue for customers paying close attention to this list when building out a vSAN cluster.
Monitoring VMware vSAN
With the latest releases of VMware vSAN, customers have a lot of great tools that are found in the box of vSphere itself that allow tremendous visibility into potential issues in the VMware vSAN environment. There are various aspects of the vSAN environment that can be monitored from the vSphere web client.
These include:
- Overall Health
- vSAN capacity
- Physical Disks
- Virtual objects
- Resynchronization
- Performance
Let’s look at each of these in a bit more detail to see how they come into play when monitoring the VMware vSAN environment.
Overall Health
The overall health dashboard for VMware vSAN provides a great overview of the health of the entire vSAN stack. You can quickly see if there are any problems that exist in the environment from the Health check dashboard. To see the overall health, navigate to Monitor > vSAN > Health to display the health status overview. As you can see below, there are evident issues in the environment that should get our attention.
vSAN Capacity
There are a number of things that can be monitored from a capacity standpoint with VMware vSAN, including the vSAN datastore, deduplication, and compression efficiency. You can also see a high-level view of how the vSAN storage is being used. Navigate to Monitor > vSAN > Capacity > Capacity Usage to see the overview of used capacity and other information.
Physical Disks
Another important health metric is in regards to the actual physical disks that are used to make up VMware vSAN storage. VMware allows administrators to have visibility into the physical disks that are being used to see any potential issues. Navigate to Monitor > vSAN > Physical Disks to see any potential issues with the physical disk health. As you can see below, there is an error regarding “Reduced availability with no rebuild” due to a physical host being taken down for maintenance.
Virtual Objects
VMware vSAN is a special kind of object storage. The Virtual Objects section under Monitoring allows viewing the state of the vSAN “objects” that comprise the virtual machine storage on the vSAN datastore.
Navigate to Monitor > vSAN > Virtual Objects to see this information. Notice the error here regarding the “reduced availability” due to a reduced physical host count participating in the vSAN datastore.
Resynchronization
When a hardware device, host, or network fails, or if a host is simply placed into maintenance mode, VMware vSAN initiates resynchronization in the vSAN cluster. The resynchronization process ensures that all data is in sync between all the VMware vSAN hosts.
Performance
Performance is an extremely critical metric that needs to be measured across any production environment. Software-defined storage including VMware vSAN is no different. The Performance dashboard found right within the vSphere client provides performance metrics and information regarding the VM, backend, and iSCSI. These can be used to troubleshoot and monitor for potential issues in the VMware vSAN environment. Navigate to Monitor > vSAN > Performance to see this dashboard.
Concluding Thoughts
VMware vSAN is the industry leader in software-defined storage found in enterprise environments today. Each version of VMware vSAN has greatly improved the visibility under the hood of the vSAN infrastructure. Effectively monitoring VMware vSAN environments is key to ensuring the environment is stable, resilient, and performant. The tools that are found in the box of vSphere client provide great baseline visibility in the areas of overall health, vSAN capacity, physical disks, virtual objects, resynchronization, and performance. By keeping a close check on the Health metrics found in the Monitor > vSAN area of the vSphere client, you can ensure a proactive approach regarding any issues that may have developed or hotspots in the vSAN environment.
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