10 Storage DRS Best Practices

Storage DRS (SDRS) is a feature of VMware vSphere that helps to optimize storage utilization and performance. It works by automatically balancing the workloads across datastores in a datastore cluster.

SDRS is a powerful tool, but it can be difficult to configure and manage. To get the most out of SDRS, it is important to follow best practices. In this article, we will discuss 10 Storage DRS best practices that will help you get the most out of your SDRS implementation.

1. Use a single datastore cluster for all of your VMs

By using a single datastore cluster, you can ensure that all of your VMs are stored on the same type of storage. This makes it easier to manage and monitor performance, as well as ensuring that all of your VMs have access to the same resources.

Additionally, having a single datastore cluster allows for more efficient use of space. Storage DRS will be able to move VMs around within the cluster in order to optimize disk usage, which helps reduce costs associated with purchasing additional storage. Finally, by having a single datastore cluster, you can easily apply policies across all of your VMs, making sure they are always running optimally.

2. Set the I/O imbalance threshold to 10% or higher

When the I/O imbalance threshold is set too low, it can cause unnecessary vMotion operations. This happens because Storage DRS will try to balance out any small differences in I/O load between datastores, even if those differences are insignificant and don’t actually affect performance.

By setting the I/O imbalance threshold to 10% or higher, you ensure that only significant imbalances in I/O load will trigger a vMotion operation. This helps reduce unnecessary resource utilization and improves overall storage efficiency.

3. Enable Storage DRS on each datastore cluster

Storage DRS helps to optimize the storage utilization of your datastore clusters by automatically balancing the workloads across them. This ensures that no single datastore cluster is over-utilized, and it also helps to prevent any one datastore from becoming a bottleneck in terms of performance or capacity.

Enabling Storage DRS on each datastore cluster also allows you to take advantage of its other features such as space utilization thresholds, I/O metrics, and affinity rules. These features help to ensure that your environment remains balanced and optimized for optimal performance.

4. Configure SDRS recommendations to be automated

Automating SDRS recommendations allows the system to make decisions on how best to balance storage resources across datastores. This helps ensure that all of your VMs are running optimally and that no single datastore is overburdened with too many VMs or too much data.

Additionally, automating SDRS recommendations can help you save time by eliminating the need for manual intervention when it comes to balancing storage resources. By configuring SDRS to be automated, you can rest assured knowing that your storage environment is being managed efficiently and effectively.

5. Disable manual mode for Storage DRS

Manual mode allows administrators to manually move virtual machines between datastores, which can lead to an unbalanced storage environment.

When manual mode is enabled, Storage DRS will not be able to make decisions about where to place VMs based on the current load and available resources. This means that it won’t be able to optimize your storage utilization or prevent over-allocation of resources.

By disabling manual mode for Storage DRS, you ensure that all VM placement decisions are made by the system itself, allowing it to maintain a balanced storage environment.

6. Ensure that you have enough storage capacity in the datastore cluster

When Storage DRS is enabled, it will attempt to balance the workload across all datastores in the cluster. If one of the datastores runs out of capacity, then Storage DRS won’t be able to move any more VMs into that datastore and performance could suffer as a result.

To avoid this issue, make sure you have enough storage capacity in your datastore cluster before enabling Storage DRS. You should also monitor the usage of each datastore regularly to ensure that none of them are running low on capacity.

7. Do not use Storage vMotion with Storage DRS

Storage vMotion is a process that moves virtual machine files from one datastore to another. When Storage DRS is enabled, it will automatically move the VM files around based on its own algorithms and rules.

If you use Storage vMotion with Storage DRS, then you are essentially overriding the decisions made by Storage DRS. This can lead to unexpected results and performance issues as Storage DRS may not be able to properly manage the resources due to the manual intervention of Storage vMotion. Therefore, it’s best to avoid using Storage vMotion when Storage DRS is enabled.

8. Avoid using multiple datastore clusters per host cluster

Using multiple datastore clusters per host cluster can lead to a number of issues, such as increased complexity and decreased performance. This is because each datastore cluster has its own set of rules for storage DRS, which means that the system must process more data in order to make decisions about where to place virtual machines. Additionally, having multiple datastore clusters can also cause contention between them, leading to slower response times when making decisions.

By avoiding using multiple datastore clusters per host cluster, you can ensure that your storage DRS environment runs smoothly and efficiently.

9. Use thick provisioned virtual disks

Thin provisioned disks are great for saving space, but they can cause performance issues when the underlying storage is running low on capacity.

When Storage DRS is enabled, it will try to balance out the load across all of your datastores. If you have thin provisioned disks, this could lead to a situation where one or more datastores become overloaded with I/O requests while others remain idle. This defeats the purpose of using Storage DRS in the first place.

By using thick provisioned virtual disks, you ensure that each disk has enough allocated capacity to handle its workload without overloading any particular datastore. This helps keep your environment balanced and ensures optimal performance.

10. Use VM anti-affinity rules when necessary

VM anti-affinity rules ensure that VMs are not placed on the same datastore. This is important for applications that require high availability, as it prevents a single point of failure from occurring if one of the datastores fails. Additionally, using VM anti-affinity rules can help to improve performance by ensuring that VMs with similar workloads are spread across multiple datastores.