Table of contents

Introduction

What is nconnect

Why it matters

How it works

Reading the numbers: what the Azure VMware Solution datastore data shows

What this unlocks for Azure VMware Solution with Azure NetApp Files

Use cases

Conclusion

Next steps

Learn more

Introduction

For the most demanding workloads, storage is rarely the limiting factor on Azure NetApp Files. More often, it is the path to storage. NFS has long used a single TCP connection per datastore per host, and while that one stream is dependable, it quietly caps how much I/O a host can drive to a datastore. The usual workaround was to spread the workload across more datastores, or more hosts, so additional connections could share the load. It worked but it meant running and managing more datastores than the workload itself ever needed.

The nconnect mount option removes that cap by letting a single NFS mount use multiple TCP connections. VMware introduced it in vSphere 8.0 Update 2, and on‑premises NetApp customers adopted it quickly to get more out of their high-speed networks and storage. Now that same option is supported on Azure VMware Solution with Azure NetApp Files. For details on the nconnect mount option, see the Azure NetApp Files Linux NFS mount options documentation.

This matters because it changes what you can expect from a single datastore with higher throughput, lower latency under concurrency, and a simpler design all without leaving the managed Azure VMware Solution platform.

Co-authors

• Rich Crofford, Azure NetApp Files Product Manager

• Pravinkumar Jeya Kumar, Senior Program Manager Azure Dedicated

What is nconnect

The nconnect option is a client-side NFS capability that allows a single NFS mount to use multiple TCP connections. Instead of sending all Azure VMware Solution datastore traffic through one stream, the client distributes it across several parallel connections driving more traffic at a lower overall latency.

Figure 1. With nconnect=4, each ESXi host opens four parallel TCP connections to a single Azure NetApp Files datastore.

ESXi introduced multiple TCP connections for a single NFSv3 datastore in vSphere 8.0 Update 2, where the capability became generally available. The number of connections is configurable per datastore and adjustable at runtime, and the default stays at a single connection, so turning it on is a deliberate choice the administrator makes.

On Azure VMware Solution, a setting of nconnect=4 is now supported with Azure NetApp Files. You can mount an Azure NetApp Files datastore with four parallel connections per host, bringing the same parallelism and performance that is proven on premises into the fully managed Azure VMware Solution. . The nconnect=4 capability is supported on both Azure VMware Solution Gen 1 and Gen 2 private clouds, so you get the same capability regardless of which generation you run.

Why it matters

The payoff shows up in the two dimensions workloads care about most.

Throughput. Four connections carry more data in parallel than one. By spreading I/O across multiple TCP streams, a single datastore connection attains more bandwidth from the same host and makes fuller use of the available network, and thus storage throughput. On the Azure NetApp Files side, those connections are serviced in parallel by the storage service, so the extra client streams translate into real aggregate throughput instead of queuing a single connection.

Latency under concurrency. This is the part that is easy to overlook. When an NFS mount is established, the storage service tracks a connection that supports a defined number of concurrent, in‑flight operations. When a busy workload exceeds that number on a single connection, the service applies flow control until operations complete and resources free up. Each pause is brief often only for microseconds but across millions of operations those pauses add up and surface as higher overall latency. Adding connections multiplies the number of operations that can be in flight at once, which reduces queuing and keeps response times consistent when the workload gets heavy. This is not just a theory. Azure NetApp Files testing with Linux NFS clients shows that adding parallel connections measurably lowers latency under concurrent load. The nconnect option brings that same mechanism to each Azure VMware Solution host.

For applications that generate sustained I/O, more throughput with higher concurrency and lower latency is exactly what is needed to run predictably.

How it works

With nconnect=4, each Azure VMware Solution ESXi host mounts an Azure NetApp Files datastore over four parallel TCP connections. Storage traffic is processed concurrently across those connections, raising aggregate throughput and supporting a higher level of I/O concurrency than a single connection model ever could.

Adoption is straightforward and non‑disruptive, for both new and existing datastores. New Azure NetApp Files datastores can be created with nconnect enabled from day one, and the option can also be applied to datastores you already run. Either way, no changes are required to your virtual machines or applications, they simply benefit from the added I/O parallelism. A single datastore can then support performance that previously took several, simplifying the environment while preserving the scalability demanding workloads rely on. Because nconnect is configured per datastore, each datastore’s connection count can be set independently to match its workload.

Reading the numbers: what the Azure VMware Solution datastore data shows

Azure VMware Solution specific nconnect benchmarks are still being run, but we do not have to wait to understand the impact. The most useful context already exists in two places; the published Azure NetApp Files datastore guidance for Azure VMware Solution, and years of Azure NetApp Files nconnect experience on Azure virtual machines. The single‑host scaling data comparing one datastore to multiple datastores is especially telling, because it shows exactly what happens when a host can spread load across more network flows.

What the published Azure VMware Solution data already tells us. With a single datastore, each Azure VMware Solution host connects over a fixed number of network flows, which became a bottleneck for the most demanding workloads. Moving from one datastore to two, and then to four, scaled out performance by giving the host more parallel network flows, as the figure below shows. That gain came purely from adding datastore level connections not from any change inside the guest virtual machines.

Figure 2. Scaling from 1 to 16 datastores on a single host lifts 8K IOPS from roughly 156,000 to 389,000 driven entirely by more parallel datastore connections.

Why that matters for nconnect. In those published single host results, moving from one datastore to four improved throughput because the host had more parallel datastore connections available. nconnect=4 changes the equation it lets a single datastore mount use four parallel TCP connections from each ESXi host. In other words, the same performance principle that previously favored multiple datastores can now be applied within a single datastore mount. That is why nconnect=4 is so significant for Azure VMware Solution with Azure NetApp Files as it helps one datastore deliver much more of the performance that used to require several.

Figure 3. Averaged across read/write mixes, scaling datastores delivers up to 397% (8KB random) and 279% (64KB sequential) relative to a single datastore the same scaling nconnect=4 brings within one datastore.

Read together, the data makes the point plainly more parallel datastore connections increase performance, and nconnect=4 brings that same scaling model to a single Azure NetApp Files datastore. These figures illustrate the scaling pattern your real‑world results will vary with the specific workload running against the datastore.

What this unlocks for Azure VMware Solution with Azure NetApp Files

Azure NetApp Files has always been the storage service of choice for the most demanding enterprise workloads databases, and high‑performance computing with no application changes required. For some of those workloads on Azure VMware Solution, the limiting factor was never the storage itself. It was the single‑connection ceiling between the host and the datastore, and nconnect=4 removes that ceiling.

Customers already running Azure VMware Solution with Azure NetApp Files can easily make use of this new feature. Because nconnect is configured per datastore, you can apply it to the datastores that are already connected and see the benefit immediately with no migration and configuration changes to your virtual machines.

Two common situations where I/O previously funneled through a single TCP flow will benefit right away: maximizing throughput for single VM with VMDKs maps to one datastore and increasing throughput for many VMs on a single datastore. In both cases, nconnect=4 relieves the bottleneck and lets the existing datastore absorb far more load which also spares you from spinning up extra datastores just to chase performance.

That is what makes Azure VMware Solution and Azure NetApp Files so compelling together. You get the enterprise grade performance of Azure NetApp Files, the familiar VMware operating model of Azure VMware Solution, and now the parallel connection scaling that high-performance workloads depend on all on a managed cloud platform.

It is worth saying plainly: with Azure VMware Solution and Azure NetApp Files, you do not need dedicated infrastructure to get bare‑metal performance. That applies to virtualized Oracle and SQL Server, to large analytics estates, and to any storage heavy application that once justified a dedicated platform. The performance is right there in the Azure VMware Solution and Azure NetApp Files platform you already run.

Use cases

The nconnect=4 option is especially valuable for Azure VMware Solution workloads that need more throughput, steadier latency under concurrency, or a simpler storage design. These use cases show where parallel TCP connections to a single Azure NetApp Files datastore make the biggest difference.

Across all of these, Azure VMware Solution backed by Azure NetApp Files delivers the performance that once required specialized or dedicated platforms while keeping the storage design simpler.

Conclusion

The nconnect option lets each Azure VMware Solution ESXi host open four parallel TCP connections to each Azure NetApp Files datastore, increasing throughput and lowering effective latency under load without adding datastores or hosts. The capability has been proven in VMware for some time, and the performance case is already backed by existing benchmark data, including Azure NetApp Files nconnect scaling on Azure virtual machines and the published one datastore versus four datastore scaling results for Azure VMware Solution.

For the workloads Azure NetApp Files is known to serve well; this was the missing piece. Databases, analytics, and other storage heavy applications now have the parallel connection scaling they need on a managed VMware platform. With Azure VMware Solution and Azure NetApp Files, you do not need specialized infrastructure to get bare‑metal performance; the performance is already there, and now it scales.

Next steps

• Review your datastore design. Identify the workloads most likely to benefit from more parallelism, especially databases, analytics platforms, and other storage‑intensive applications that currently span multiple datastores mainly for performance.
• Validate platform prerequisites. Confirm that your Azure VMware Solution environment and Azure NetApp Files datastore deployment follows the documented connectivity and performance best practices for attached datastores, including the guidance for your generation of private cloud.
• Test nconnect on the right datastores first. Start with the datastores that show the clearest signs of throughput pressure or latency under concurrency, then compare performance and operational simplicity before expanding more broadly.
• Standardize across the cluster. Apply a consistent configuration across hosts for any datastore that uses nconnect, so performance characteristics and mobility operations stay predictable.
• Use the published guidance to plan rollout. Review the Azure VMware Solution attach guidance, performance considerations, and benchmark documentation to decide where nconnect can help you reduce datastore sprawl while preserving the performance your workloads require.

For Azure VMware Solution customers using Azure NetApp Files, nconnect is a practical way to simplify storage design while improving throughput and latency for demanding workloads. It helps you get more from the datastores you already use, with less need to spread workloads across additional datastores just to add parallelism.

Learn more

• What’s new in Azure NetApp Files
• Azure NetApp Files datastore performance benchmarks for Azure VMware Solution
• Azure VMware Solution datastore performance considerations for Azure NetApp Files
• Attach Azure NetApp Files datastores to Azure VMware Solution hosts
• Azure NetApp Files Linux NFS mount options
• NFS mount Linux manual