10 VMware SCSI Controller Best Practices

The VMware SCSI controller is a key component of the VMware vSphere virtualization platform. It provides high-performance storage connectivity for virtual machines running on a vSphere host.

In this article, we will discuss 10 best practices for configuring and using the VMware SCSI controller in your vSphere environment.

1. LSI Logic SAS is the default controller for new virtual machines

LSI Logic SAS is a high-performance storage controller that supports up to 256 devices and provides excellent compatibility with a wide range of storage devices. It also offers good scalability, so it can be used in small and large deployments alike.

Using LSI Logic SAS as the default controller will help ensure that your virtual machines have the best possible storage performance and compatibility.

2. VMware Paravirtual is the best performing SCSI controller type

The VMware Paravirtual controller type is a high-performance SCSI controller that uses the VMware PVSCSI driver. The PVSCSI driver is a special purpose driver that has been optimized for use with virtual disks. The PVSCSI driver offloads most of the I/O processing to the VMkernel, which reduces CPU utilization in the guest operating system.

The PVSCSI driver also supports up to 64 logical units (LUNs) per controller, which is twice the number supported by the other SCSI controller types. This allows you to create more virtual disks on a single controller without sacrificing performance.

3. Use PVSCSI controllers on high-throughput workloads

PVSCSI controllers are a type of controller that is designed specifically for high-throughput workloads. They offer a number of benefits over other types of controllers, including:

1. Increased throughput – PVSCSI controllers can handle more I/O than other types of controllers, making them ideal for high-throughput workloads.

2. Reduced CPU utilization – PVSCSI controllers use less CPU than other types of controllers, freeing up resources for other tasks.

3. Improved performance – PVSCSI controllers offer improved performance over other types of controllers, making them ideal for mission-critical applications.

4. Enhanced compatibility – PVSCSI controllers are compatible with a wide range of operating systems and applications, making them a good choice for mixed-environment deployments.

5. Easy to use – PVSCSI controllers are easy to configure and use, making them a good choice for users who are new to VMware.

4. Use a single PVSCSI adapter per VM with up to 15 disks

The PVSCSI controller is designed for high-performance storage I/O and can greatly improve the storage performance of your VM. However, if you use multiple PVSCSI adapters in a single VM, you will actually decrease the overall storage performance because the controllers will contend with each other for resources.

Additionally, using more than one PVSCSI adapter per VM can also lead to increased CPU utilization due to the additional overhead required to manage the multiple controllers. For these reasons, it is best to use a single PVSCSI adapter per VM whenever possible.

5. Add additional adapters if you have more than 15 disks

The first reason is that by adding additional adapters, you’re increasing the number of available I/O paths to your disks. This can help improve performance and prevent contention issues.

The second reason is that if you have a disk failure, you’ll still have access to your data through the other adapters. This is because each adapter has its own set of disks, so if one adapter fails, the others can still be used.

Adding additional adapters is a simple process and only takes a few minutes, so it’s well worth doing to ensure optimal performance and reliability for your VMware environment.

6. Use LSI Logic SAS for compatibility and legacy support

The LSI Logic SAS controller is the most compatible with a wide range of operating systems and devices. It’s also backward compatible with older SCSI standards, which is important for organizations that need to maintain legacy systems.

Using the LSI Logic SAS controller will ensure that your VMware environment is compatible with the widest range of devices and operating systems possible. It’s also the best choice for organizations that need to maintain legacy SCSI support.

7. Use BusLogic Parallel when migrating from older operating systems

When you’re using an older operating system, the default VMware SCSI controller is LSI Logic Parallel. However, this controller isn’t supported by newer versions of VMware ESXi. So, if you try to migrate your VM from an older version of ESXi to a newer one, you’ll get an error saying that the LSI Logic Parallel controller isn’t compatible.

To fix this, you need to change the controller to BusLogic Parallel before you migrate. Once you’ve done that, you’ll be able to successfully migrate your VM to the new version of ESXi.

8. Do not use IDE controllers in production environments

IDE controllers are designed for lower-end hardware and do not offer the same level of performance or features as SCSI controllers. In addition, IDE controllers do not support certain advanced features that are available on SCSI controllers, such as hot plugging and dynamic expansion.

Using a SCSI controller in your VMware environment will provide you with better performance and more features than an IDE controller.

9. Convert existing VMs from LSI Logic SAS to PVSCSI

The LSI Logic SAS controller is the default controller type in VMware, and has been for many years. It’s a good all-around controller that works well with a variety of workloads.

However, the PVSCSI (Paravirtual SCSI) controller is a newer controller type that offers much better performance for certain types of workloads, such as storage intensive applications.

Therefore, if you have any VMs running on LSI Logic SAS controllers that are doing storage intensive work, it’s a good idea to convert them to PVSCSI controllers. The performance improvement can be significant, and it’s a relatively easy process to do.

10. Use multiple vCPUs with PVSCSI controllers

When you use a single vCPU with a PVSCSI controller, the I/O operations are processed in series instead of in parallel. This can lead to lower performance because each I/O operation has to wait for the previous one to finish before it can start.

However, when you use multiple vCPUs with a PVSCSI controller, the I/O operations are processed in parallel, which can lead to much higher performance. In fact, using multiple vCPUs can increase the performance of your PVSCSI controller by up to 1000%.

So, if you’re looking to get the most out of your PVSCSI controller, make sure to use multiple vCPUs.