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Sizing Calculator


Example of Hardware Sizing

This example shows an initial GMS and CS cluster deployment and ensures that performance is correct in scale.

In this example, GMS and CS and later instance is used with external Cassandra 2.0.8.

Host Specifications Software Components
4 similar hosts Windows Server 2008 R2 Standard SP 1

Intel Xeon X3440 @ 2.53 GHz, quad core
Low Price disks

JMeter 2.11

GMS and later
Xmx is 2G for java
Cassandra 2.0.8 external

Genesys Framework Windows Server 2008 R2 Standard SP1 Runs Genesys Framework/Suite 8:
  • Config Server:
  • DB Server:
  • Message Server:

GMS and CS are configured to handle a constant average CPU of 50%. This allows for burst and Cassandra background activities to happen correctly, high load prevent cleaning to occur correctly, and increasing latencies over time.


Start from a database with 2.5GB data on each node. Complex statistics (requiring fetch of "start" event during processing of "end" event) are enabled for States/Tasks. All statistics are available for Services.

Special settings and enhancements:

  • Cassandra 2.0.8
  • Replication Factor = 2
  • Consistency Level = 1/1 (read/write)
  • Correctly Balanced Cassandra node tokens for each node to own 25% data


  • cview/data-validation=false


  • Modified to add constant time between events (200ms), allowing constant load of GMS nodes


Captured measure Value Comments
Database size 68 GB / node (after 120h+ run by set of 48h) = 272 GB 272 GB corresponds to 16.5 M conversations or 264 M activities that make a ratio of 0.54KB for each activity. Multiply by replication factor to reflect correct disk size.
Throughput Approximately1000 tx/s (approximately 30.5 scenario/s) Constant through 24h testing
Size of conversation Approximately10kB in JSON This matches a conversation of 16 activities, with extension data as returned by Query Service, State, and Tasks by CustomerId
CPU Approximately 20% to 60% Each node was around an average of 30% with peaks to 60% from time to time
Memory 2.4GB For each GMS process, less than 2 GB for Cassandra processes.
I/O Disc Approximately 3 MB/s (Cassandra measure) Disk I/Os fluctuate a lot (between 0 MB/s and 20 MB/s)
I/O Network Approximately 3 MB/s Between 20Mbps and 60Mbps.


This test showed successful long running tests for more than 48h with an average of 1000 tx/s on a 4 node cluster GMS with external Cassandra 2.0.8. To scale on higher throughput, you should allow more nodes into the cluster.

In the testing environment, it was possible to have up to 2x better throughput but Cassandra could not sustain very long before getting late in compaction state, resulting in increase of latencies after a few hours load (4-8h).

The throughput tested in this scenario is about 2x maximum speed required (approximately 25 CAPS, approximately 400 tx/s expected).


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This page was last modified on 3 March 2017, at 07:06.