Multapplied SD-WAN supports virtualization for all host types- management servers, aggregators, and bonders. Virtualization makes it easy to provision and manage hosts but adds complexity for managing performance when multiple guests compete for the resources of a single host.
The following best practices are intended for aggregators and bonders, since as a core part of your customer data network, they are very sensitive to resource availability. Management servers should be configured using practices generally accepted for web and database applications; for example, management server requirements focus on memory size and storage performance rather than CPU and network performance.
The ideas here are applicable to all virtualization environments.
Best Practices
Following these recommendations will help maximize the performance and reliability of your SD-WAN environment.
Host Configuration
Host clock should be configured using NTP. A misconfigured host clock will cause guest clocks to shift back and forth between the wrong host time and accurate guest time, causing a variety of serious errors.
Storage Considerations: Local storage – use mirrored RAID drive configuration for reliability; Network storage – storage traffic should use a different network than SD-WAN traffic
Multapplied SD-WAN Guest VM Configuration and Resource Assignments
The following recommendations apply to aggregator or bonder guests.
CPU
- Do not over-allocate vCPUs. Begin with 2 vCPUs for a small environment (10 bonds or less). You can easily scale up later.
- Reserve 1 GHz or more.
Memory
- Do not over-allocate memory. Begin with 512 MB for a small environment.
- Reserve all memory- ie, set the reserved memory equal to the configured memory. This will prevent the host from swapping guest memory to disk, which is devastating for performance.
Storage
- Aggregators and bonders use very little storage. Virtual disks can be small (8 GB), thin provisioning is acceptable, and storage IO reservations are not required.
Network
- NICs should be VMXNET 3 for optimum performance.
- Consider setting up network resource reservations, depending on your network design and usage patterns.
Multapplied SD-WAN Guest OS Configuration
- Install VMware tools. The open source tools are acceptable; these can be installed from standard Debian repositories with:
apt-get install open-vm-tools -y
service bonding restart - Ensure the guest clock is configured using NTP. This is the default for all Multapplied SD-WAN nodes.
Multapplied SD-WAN Guest OS Configuration
Ensure other guests on the same physical hardware as Multapplied SD-WAN guests are “rightsized”- that they have not been assigned more resources than necessary. Failure to assign resources appropriately, especially for virtual CPUs, can result in contention and actually reduce the performance of all guests on the host. See the Resources section below for information on rightsizing a Virtual Machine environment.
Key Metrics
The following metrics are useful for ensuring good performance. They are reported in vSphere Client. We don’t offer recommendations for memory size and network rates, as these metrics depend on your usage patterns.
| Metric | Recommended Value | Comments |
|---|---|---|
| CPU Usage | < 80% | Higher values indicate that the CPU allocation is too low. |
| CPU Ready | < 2.5% | Higher values indicate a higher proportion of time that the guest has tasks to process but is waiting to be scheduled. |
| Memory Ballooned | 0 | Ballooned memory indicates that the guest's memory reservation is too low or the host memory overcommitment ratio is too high. |
| Memory Swapped | 0 | Swapped memory indicates that the guest's memory allocation or reservation is too low. Its performance may be significantly reduced. |
| Disk Bus Resets | 0 | Bus resets can indicate overcommitment or hardware failures that can cause guests to hang or crash. |
| Disk Commands Aborted | 0 | Commands aborted can indicate overcommitment or hardware failures that can cause guests to hang or crash. |