VMware

Certain Verba server roles run real-time media applications, and as such require low-latency access to resources to perform according to specification and to sizing guidelines. This document provides an overview of the recommendations for provisioning the servers in a VMware environment. Failure to follow the configuration recommendations provided can result in the loss of recording, application functionality, and data loss.

Version support

The use of VMware ESXi versions 5.5, 6.0, 6.5, and 6.7 (also referred to as VSphere 5.5, 6.0, 6.5, and 6.7) is supported for all server roles.

Recommendations

The following table lists the recommendations for VMware deployments for the specific server roles:

	Recommendation	Applicable Server Roles
Memory	Set 100% memory reservation. Reserving physical RAM on the VM guest prevents memory ballooning from occurring. If memory ballooning does occur, due to insufficient physical RAM, delays and recording loss can occur due to memory swapping.	Recording Server Media Collector and Proxy Server Announcement Server
Memory	Set with the appropriate size in GBs (according to server role)	All
CPU	Reserve 100% of the CPU, which guarantees exclusive pCPU access, which in turn helps to reduce vCPU halt/wake-up cost	Recording Server Media Collector and Proxy Server Announcement Server
	Do not over-provision pCPUs, because it can lead to performance impacts because of additional sharing of last-level cache (LLC) and reduces the performance of latency-sensitive VMs that use virtual NICs (vNICs) for network I/O	Recording Server Media Collector and Proxy Server Announcement Server
	Configure the appropriate number of vCPUs (defined in the sizing guide according to server role)	All
	The physical host must have extra processing available for scheduling, network handling, device interrupt handling, and other related tasks. To prevent any loss of recording, do not over-commit the CPUs on a host. The equivalent of one physical CPU core must be available to handle these tasks.	All
Disk	Disk subsystem should be correctly sized based on the required capacity and performance	Recording Server
Network	Enable promiscuous mode on the virtual interface when network port mirroring (passive) recording is used	Recording Server Media Collector and Proxy Server
	The VMXNET3 driver should be used for any NICs that are being used for recording unless the NIC is configured as a pass-through mechanism (such as SR-IOV) to bypass the network virtualization layer, in which case the native driver is required. Enable Receive Side Scaling (RSS) for high-performance network settings. Network driver configuration settings: Large Rx buffers: 8192 Byte (max) Max Tx queues: 8 (max) Maximum number of RSS processors: 8 (max) Receive Side Scaling: enabled RSS base processor number: not preset (default) Rx ring #1 size: 4096 Byte Rx ring #2 size: 4096 Byte Small Rx buffers: 8096 Byte Tx ring size: 4096 Byte Wake on magic packet: disabled Wake on pattern match: disabled	Recording Server Media Collector and Proxy Server Announcement Server
	Recorder servers perform real-time processing, making them latency-sensitive. VMware recommends the use of its latency-sensitivity features in such an environment to virtualize the Recorder and associated applications: To bypass the network virtualization layer, if the hardware supports it, use a passthrough mechanism such as SR-IOV To avoid contention for network bandwidth, use a separate physical NIC (pNIC) for latency-sensitive VMs If you do not use a passthrough mechanism and there is contention for network bandwidth, use Network I/O Control (NetIOC)	Recording Server Media Collector and Proxy Server Announcement Server
Other	Install the VMWare Tools application on the VM guest machines	All
	Make all power management unavailable in both the Basic Input/Output System (BIOS) and vSphere.	All
	Do not use snapshotting in business hours, because snapshotting causes the VM host to pause execution on virtual machines. Sometimes, all virtual machines on the host are paused. Use of snapshotting during business hours can result in recording loss.	Recording Server Media Collector and Proxy Server Announcement Server
	Do not use High Availability (HA), vMotion, and Distributed Resource Scheduler (DRS) in business hours, because these features cause the VM host to pause execution on virtual machines. Sometimes, all virtual machines on the host are paused. Use of these features can result in recording loss.	Recording Server Media Collector and Proxy Server Announcement Server

If the required CPU and memory resources are not available for the VMs, problems will manifest during high-stress periods. During high-stress periods, use of system resources in real-time rapidly increases. Reserving the required resources ensures the integrity of the system and its performance at the stated level in all conditions. When reservations are not set correctly, the following problems can occur:

Excessive packet drops can lead to data loss
Shared memory and memory ballooning can cause recording loss because memory is used by other virtual machines and is not instantly available
Shared CPUs can cause recording and packet loss when sudden surges of network activity require more processing power
Incorrectly sized disk subsystems cause recording loss when shared by multiple applications.

Additional information

The following documents from VMware discuss how to virtualize latency-sensitive applications: