Network Management

Impact of using SQL Express server for flow data storage

If you install an evaluation copy of NTA 4.4 or later, NTA automatically deploys the SQL Express server for storing your flow data. The performance of this SQL server edition is lower than the performance of SQL Standard or Enterprise editions. Learn more about deploying SQL Express with NetFlow Traffic Analyzer (NTA).

First published date

10/18/2018 7:56 PM

Last published date

10/16/2025 5:40 PM

Overview

If you install an evaluation copy of NTA 4.4 or later, NTA automatically deploys SQL server Express for storing your flow data. As of NTA 2020.2, you can use the Express edition of SQL server also in production environments.

Product section

Netflow Traffic Analyzer

Resolution

If you install an evaluation copy of NTA 4.4, NTA automatically deploys the SQL Express server for storing your flow data.
In comparison with the Standard or Enterprise edition, using SQL server Express has the following limitations:

  • Limitation of maximum memory utilized - affects performance
  • Limitation of maximum database size - affects the flow count limit which can be exhausted very quickly
  • SQL Express uses only single CPU - affects performance

As of NTA 2020.2, you can use the Express edition of SQL server also in production environments. See the following recommendations before you use SQL server Express in your production environment:

  • Due to the limit 1.4 GB RAM, make sure you use separate SQL server Express instances for NTA Flow Storage database and the Orion database.
  • If possible, use SSD disks. With limited RAM size, SQL server Express will access the disc more frequently than the Standard edition. Due to the SQL server Express limitation, the size of the database will not exceed 10 GB.
  • SolarWinds recommends you avoid using license tiers higher than SL100 or SL250.
  • Make sure you are not resolving and storing IPv4 hostnames immediately when a flow record is received.
  • Keep top talker optimization on the default value of 95%.
  • With the default 30-day retention period, NTA is capable of processing approximately 150 inserts per second which corresponds to approximately 5000 fps. This limitation is for the whole system and not per polling engine. To process more flows on the environment, you need to decrease the retention period. For example, 17500 fps (500 inserts per second) generates approximately 1.1 GB of data per day, so you should decrease the retention period to 5 days.
  • To decrease the fps sustained, SolarWinds recommends you use sampling for flow exporting on the routers.