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Tag Archives: vSphere 6.7 U1

Storage DRS Performance Improvements in vSphere 6.7

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Virtual machine (VM) provisioning operations such as create, clone, and relocate involve the placement of storage resources. Storage DRS (sometimes seen as “SDRS”) is the resource management component in vSphere responsible for optimal storage placement and load balancing recommendations in the datastore cluster.

A key contributor to VM provisioning times in Storage DRS-enabled environments is the time it takes (latency) to receive placement recommendations for the VM disks (VMDKs). This latency particularly comes into play when multiple VM provisioning requests are issued concurrently.

Several changes were made in vSphere 6.7 to improve the time to generate placement recommendations for provisioning operations. Specifically, the level of parallelism was improved for the case where there are no storage reservations for VMDKs. This resulted in significant improvements in recommendation times when there are concurrent provisioning requests.

vRealize automation suite users who use blueprints to deploy large numbers of VMs quickly will notice the improvement in provisioning times for the case when no reservations are used.

Several performance optimizations were further made inside key steps of processing the Storage DRS recommendations. This improved the time to generate recommendations, even for standalone provisioning requests with or without reservations.

Test Setup and Results

We ran several performance tests to measure the improvement in recommendation times between vSphere 6.5 and vSphere 6.7. We ran these tests in our internal lab setup consisting of hundreds of VMs and few thousands of VMDKs. The VM operations are

  1. CreateVM – A single VM per thread is created.
  2. CloneVM – A single clone per thread is created.
  3. ReconfigureVM – A single VM per thread is reconfigured to add an additional VMDK.
  4. RelocateVM – A single VM per thread is relocated to a different datastore.
  5. DatastoreEnterMaintenance – Put a single datastore into maintenance mode. This is a non-concurrent operation.

Shown below are the relative improvements in recommendation times for VM operations at varying concurrencies. The y-axis has a numerical limit of 10, to allow better visualization of the relative values of the average recommendation time. 

The concurrent VM operations show an improvement of between 20x and 30x in vSphere 6.7 compared to vSphere 6.5 

Below we see the relative average time taken among all runs for serial operations.

The Datastore Enter Maintenance operation shows an improvement of nearly 14x in vSphere 6.7 compared to vSphere 6.5

With much faster storage DRS recommendation times, we expect customers to be able to provision multiple VMs much faster to service their in-house demands. Specifically, we expect VMware vRealize Automation suite users to hugely benefit from these improvements.

SPBM compliance check just got faster in vSphere 6.7 U1!

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vSphere 6.7 U1 includes several enhancements in Storage Policy-Based Management (SPBM) to significantly reduce CPU use and generate a much faster response time for compliance checking operations.

SPBM is a framework that allows vSphere users to translate their workload’s storage requirements into rules called storage policies. Users can apply storage policies to virtual machines (VMs) and virtual machine disks (VMDKs) using the vSphere Client or through the VMware Storage Policy API’s rich set of managed objects and methods. One such managed object is PbmComplianceManager. One of its methods, PbmCheckCompliance, helps users determine whether or not the storage policy attached to their VM is being honored.

PbmCheckCompliance is automatically invoked soon after provisioning operations such as creating, cloning, and relocating a VM. It is also automatically triggered in the background once every 8 hours to help keep the compliance records up-to-date.

In addition, users can invoke the method when checking compliance for a VM storage policy in the vSphere Client, or through the VMware Storage Policy API method PbmCheckCompliance.

We did a study in our lab to compare the performance of PbmCheckCompliance between vSphere 6.5 U2 and vSphere 6.7 U1. We present this comparison in the form of charts showing the latency (normalized on a 100-point scale) of PbmCheckCompliance for varying numbers of VMs.

The following chart compares the performance of PbmCheckCompliance on VMFS and vSAN environments.

As we see from the above chart, PbmCheckCompliance returns results much faster in vSphere 6.7 U1 compared to 6.5 U2. The improvement is seen across all inventory sizes and all datastore types and become more prominent for larger inventories and higher numbers of VMs.

The enhancements also positively impact a similar method, PbmCheckRollupCompliance. This method also returns the compliance status of VMs and adds compliance results for all disks associated with these VMs. The following chart represents the performance comparison of PbmCheckRollupCompliance on VMFS and vSAN environments.

Our experiments show that compliance check operations are significantly faster and more light-weight in vSphere 6.7 U1.