4 whitepapers från performance teamet på VMware.

VMware vCloud Director 1.5 Performance and Best Practices

VMware vCloud Director gives enterprise organizations the ability to build secure private clouds that dramatically increase datacenter efficiency and business agility. Lots of new features have been added to vCloud Director 1.5 to accelerate application delivery in the cloud. In this paper, we discuss some of the features of the vCloud Director 1.5 release, performance characterizations including latency trends, resource consumptions, sizing guidelines and hardware requirements, and performance tuning tips.

Some highlights of vCloud Director performance and best practices include:

• When using fast provisioning (linked clones) and a VMFS datastore, do not exceed eight hosts in a cluster.
• Be aware that there is a chance to hit the snapshot chain length limit. If the current clone has become very slow compared to the prior clone, the clone may have hit the snapshot chain length limit 30. This can be resolved by virtual machine consolation.
• For virtual machines that are not generating I/O-intensive workloads, linked clones offer the flexibility and agility of instant provisioning.
• For cross-vCenter and cross-datastore linked clones, pre-allocating the vApp to the target datastore helps shorten the subsequent copy time.

For more details and performance tips, please refer to VMware vCloud Director 1.5 Performance and Best Practices

Site Recovery Manager 5.0 Performance and Best Practices

VMware vCenter Site Recovery Manager (SRM) 5.0 provides business continuity and disaster recovery protection for VMware virtual environments. Protection can range from virtual machines (VMs) residing on a single, replicated datastore to all the VMs in a datacenter.
A new technical white paper about SRM has been published. In it, we look at several performance characteristics of SRM, including scalability and recovery, and how they behave in an environment that simulates real-life workloads. The paper includes several recommendations to enhance the performance of SRM and reduce recovery time. A couple of recommendations include:

• It is a good practice to have fewer but larger NFS volumes so that the time taken to mount a large number of such volumes decreases during the recovery. This might also translate to fewer protection groups on your setup leading to reduced recovery time.
• Configuring VM dependencies across priority groups instead of setting per VM dependencies is usually the best idea because VMs within each priority group will be started in parallel.

Please refer to VMware vCenter Site Recovery Manager 5.0 Performance and Best Practices for more recommendations, charts, and key takeaways.

VoIP Performance on vSphere 5

The majority of business-critical applications such as Web applications, database servers, and enterprise messaging systems have been successfully virtualized, proving the benefits of virtualization for reducing cost and streamlining IT management. However, the adoption of virtualization in the area of latency-sensitive applications has been slow partly due to unsubstantiated performance concerns. By taking VoIP service as an example, a newly published white paper demonstrates that vSphere 5 brings the same virtualization benefits to latency-sensitive applications. In particular, the paper shows that vSphere 5 delivers excellent out-of-the-box performance in terms of voice quality when running VoIP service.

The evaluation results demonstrate that good voice quality is maintained when the number of users (number of voice streams) and media server instance increased, while fully utilizing CPU. For example, vSphere 5 is able to maintain great VoIP performance even when running 12 instances of VoIP media server configured with a total of 48 vCPUs on a system with 8 cores. It is further shown that the NetIOC feature is able to prevent packet loss successfully, thereby helping to preserve voice quality under severe contention for network.
Read more about the VoIP Performance Evaluation on VMware vSphere 5.

Network I/O Latency on vSphere 5

Network I/O latency is an important measurement, especially in latency-sensitive applications like those found in industries such as finance and trading, healthcare, transportation, and telecom (in particular, applications using Voice over IP). The end-to-end latency requirements of these applications vary from microseconds to milliseconds. And some of these applications, such as those utilizing Voice over IP, are more sensitive to jitter than end-to-end latency. So an important measurement to consider for vSphere performance in this scope is latency and jitter added due to virtualization.

vSphere performance testing in a recently published white paper shows that there is minimal network I/O latency due to virtualization overhead. The paper looks at several aspects of network I/O latency, including:

• Latency overhead due to virtualization per VM per round-trip
• Round-trip latency between two virtual machines on the same vSphere host
• Impact of using DirectPath I/O on virtual machine response time
• Impact of resource (CPU, network bandwidth) contention on virtual machine response time

The paper also includes consolidation guidelines and best practices that can reduce network I/O latency in your vSphere system.
Read more about Network I/O Latency on VMware vSphere 5.