Sizing Service Engines

Overview

Avi Networks publishes minimum and recommended resource requirements for new Avi Service Engines. However, network and application traffic may vary.  This guide provides some guidance on sizing.  You can consult with your local Avi sales engineer for more recommendation that is tailored to the exact requirements.

Note for deploying into AWS: The Installing Avi Vantage in Amazon Web Services article provides additional sizing guidance unique to the AWS environment, including this link to Amazon’s own guidance on various maxima.

The below per-CPU-core data are obtained using Intel v4 CPUs:

1 CPU core
L4 Throughput 5 Gbps
L7 Throughput 3 Gbps
Connections/s 40k
SSL Throughput 1 Gbps
SSL TPS (RSA2K) ~1,000
SSL TPS (ECC) 2500

Multiple performance vectors or features may have an impact on performance. For instance, to achieve 1 Gbps of SSL throughput and 2000 TPS of SSL with EC certificates, it is recommended to have two cores.

Avi Service Engines can be configured with as little as 1 vCPU core and 1 GB RAM, or up to 64 vCPU cores and 256 GB RAM.  In write access mode, Service Engine resources for newly created SEs can be configured within the SE Group properties.  When creating an Avi SE in read or no access modes, Avi SE resources are allocated manually by an administrator via the hypervisor or by the size hardware used for bare metal servers.

CPU

CPU scales very linearly as more cores are added. Note that Avi Vantage cannot differentiate between a physical core and a hyperthreaded core, which generally provides reduced performance compared to a physical core. CPU is a primary factor in SSL handshakes (TPS), throughput, compression, and WAF inspection. For vCenter clouds, the default is 2 CPU cores, not reserved. However, CPU reservation is encouraged.

Memory

Memory scales near linearly. It is used for concurrent connections and HTTP caching. Doubling the memory will double the ability of the Avi Service Engine to perform these tasks. The default is 2 GB memory, reserved within the hypervisor for VMware clouds. Refer to SE Memory Consumption for more details.

PPS

For throughput-related metrics, the hypervisor is likely going to be the bottleneck.  Limitations are different for each hypervisor and version. For instance, VMware’s vSphere/ESX 5.x supports about 550k packets per second to a virtual machine such as Avi’s Service Engine. ESX version 6 doubles this number to around 1.2M PPS. Bare metal (no hypervisor) numbers depend on the type of NIC used. For DPDK mode, 82599, X520, X540, X550, X552, X710, and XL710 are the supported Intel NICs. DPDK can be used in some environments to bypass PPS limitations of the hypervisor and provide line rate speeds.

Disk

Avi Service Engines may store logs locally before they are sent to the Avi Controllers for indexing. Increasing the disk will increase the log retention on the SE. SSD is preferred over hard drives, as they can write the log data faster. This is not a requirement. The recommended minimum size for storage is 10 GB, ((2 * RAM) + 5 GB) or 10 GB, whichever is greater. 10 GB is the default for SEs deployed in VMware clouds.

Disk Capacity for Logs

Avi Vantage computes the disk capacity it can use for logs based on equations incorporating the following parameters:

  • T, the SE’s total disk capacity
  • N, the number of CPU cores
  • M, the main memory (RAM) of the SE
  • p, log_agent_max_storage_ignore_percent, a parameter in SE runtime properties
  • D, the capacity reserved for debug logs
  • C (reserved for cores), 2 * M
  • MIN, the minimum size allocated for logs
  • L, the capacity reserved for client logs

Avi Vantage calculates D as follows:


D = p * T / 100

Initially, Avi Vantage sets L, the client log size, as follows:


L = T - D

Finally, Avi Vantage adjusts L and C based on the following conditions:

  
  if L > C + MIN, then set L to (L - C)
    else if L > MIN, then set C to L - MIN and then set L to MIN
       else set C to 0