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Performance Comparison of Physical Server and Virtual Machines

Single Hex Core

With a single hex core CPU, Genesys recommends 200 ports as a reasonable peak port capacity on a physical server with a single X5670, assuming that all criteria have been met. 300 ports can be achieved with a three-VMs configuration of the same hardware, with a single X5675 (performance is slightly better than X5670). The graph below compares overall CPU usage:

Figure 1: Comparison of System Usage between Physical Server and VM from Single Hex Core


Memory usage for MCP scales linearly against port capacity:

Figure 2: Comparison of MCP Memory Usage between Physical Server and VM from Single Hex Core


The two graphs below compare the 95th percentile value of Max Jitter Buffer and Max Delta, tracking audio quality from a sample RTP stream:

Figure 3: Comparison of Max Jitter between Physical Server and VM from Single Hex Core
Figure 4: Comparison of Max Delta between Physical Server and VM from Single Hex Core


A strong correlation exists between Max Jitter Buffer and Max Delta, regarding audio quality. A physical server can meet all criteria when its port capacity is 200 or below. Port capacity that is between 200 and 220 may impact audio quality, since both Max Jitter buffer and Max Delta are just slightly beyond the passing criteria. You can consider 220 as peak performance, if audio quality is not strictly required and can be waived. However, when port capacity reaches 230 or beyond, the two values become so big that there is apparent audio quality impact.

For VM configuration: Preferred/Recommended = 300 ports; Peak Port Capacity = 360 ports. With 390 ports, overall system CPU usage is 97%, close enough to 100% that it also observed audio quality impact.

Below are two tables of IOPS for the above two configurations:

Table 1: Disk IOPS of system level from a physical server with a single hex core

Ports Disk IOPS Physical Server
Total Reads Writes
60 11.13 0.001 11.13
120 21.82 0.001 21.82
180 32.03 0.001 32.03
200 34.95 0.001 34.95
210 36.53 0.001 36.53
220 37.76 0.001 37.76
230 39.48 0.001 39.48
240 43.33 0.002 43.33

Table 2: Disk IOPS of sum of all VMs of single hex core

Ports Disk IOPS VMs Overall
Total Reads Writes
120 20.68 0.101 20.58
240 36.29 0.070 36.22
270 41.39 0.087 41.30
300 45.57 0.065 45.50
330 48.85 0.000 48.85
360 51.69 0.000 51.69
390 57.82 0.002 57.82

Disk IOPS in Disk IOPS of sum of all VMs of single hex core table is the sum of Disk IOPS from all VMs. Also, IOPS is measured from each VM and then totaled, to determine overall IOPS. The same method is applied to all Disk IO calculations for VM environments in this series of tests.

Also in the above two tables, the IOPS Reads value is quite small because most of the operations are Writes.

The graph below compares the two IOPS tables above:

Figure 5: Comparison of System Disk IOPS Physical Server and VM from Single Hex Core
  • System level disk IOPS is scaling linearly against port capacity for both physical server and virtual machines.
  • SSD is only used on VM env as cache folder of MCP recording while SAS HDD drive is used to installed OS and MCP.

Dual Hex Cores

With a host of dual hex core CPUs (2x X5675@3.06GHz) with 32 GB RAM, we also compare the results from physical server and VM env. In VM env, on same hardware spec, 3 VMs are configured with 4 vCPU and 8 GB RAM assigned to each VM. Only one MCP installed on each VM and a SSD partition is used as cache folder for MCP recording.

The graph below depicts the overall system CPU usage:

Figure 6: Comparison of System Usage between Physical Server and VM from Dual Hex Cores


The next two graphs show 95 percentile values of Max Jitter and Max Delta from sample RTP stream quality analysis:

Figure 7: Comparison of Max Jitter between Physical Server and VM from Dual Hex Cores
Figure 8: Comparison of Max Delta between Physical Server and VM from Dual Hex Cores


The two tables below show:

  • Disk IOPS at system level on a physical server.
    and
  • Disk IOPS at system level on a VM environment.

Table 3: Disk IOPS at system level from physical server of dual hex cores

Ports Disk IOPS Physical Server
Total Reads Writes
50 9.069 0.000 9.07
100 18.587 0.000 18.59
150 28.598 0.001 28.60
200 37.460 0.001 37.46
240 41.290 0.003 41.29
280 49.031 0.020 49.01
330 53.373 0.001 53.37
350 53.150 0.001 53.15
380 61.456 0.001 61.46
400 64.123 0.001 64.12


Table 4: Disk IOPS of sum of all 3 VMs of dual hex cores

Ports Overall Disk IOPS
Total Reads Writes
120 22.38 0.024 22.35
240 38.99 0.012 38.97
300 48.60 0.017 48.59
360 56.05 0.047 56.00
390 60.24 0.002 60.24
420 64.59 0.028 64.57

The graph below compares the above two tables above:

Figure 9: Comparison of System Disk IOPS Physical Server and VM from Dual Hex Cores

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This page was last modified on 11 July 2018, at 01:47.