Network Management

Maximum size of the SQL Express database for flow data storage

Using Microsoft SQL server Express server for storing your flow data has specific limitations, such as maximum database size.

First published date

11/13/2018 7:37 PM

Last published date

10/16/2025 5:38 PM

Overview

If you install an evaluation copy of NTA 4.4 or later, NTA automatically deploys Microsoft SQL server Express for storing your flow data. Using the Express edition of SQL server in a production environment has specific limitations, such as maximum database size.

Product section

Netflow Traffic Analyzer

Resolution

NTA 2020.2 and later

As of NTA 2020.2, you can use the Express edition of SQL server also in production environments, but there are certain recommendations you should consider:

  • Due to the limit 1.4 GB RAM, make sure you use separate SQL server Express instances for the NTA Flow Storage database and the Orion database.
  • If possible, use SSD disks. With limited RAM size, SQL server Express will access the disk 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. The NTA Summary page load speed is approximately 5 seconds in an environment with 4 cores, 8 GB RAM, and using no SSDs.
  • To decrease the fps sustained, SolarWinds recommends you use sampling for flow exporting on the 

NTA 4.4 through 2019.4

In NTA 4.4 through 2019.4, Microsoft SQL server Express is not recommended for production deployment due to limitations, such as maximum database size. This affects the flow count limit, which can be exhausted very quickly.

Using Microsoft SQL server Express with NTA 4.4 through 2019.4 has the following limitations:

  • Microsoft SQL Server 2016 Express edition has a database size limit of 10 GB. When you are close to reaching the SQL Express database size limit, you will receive a warning message.
    • The database limit of 10 GB is for each database on the SQL server.
  • The CPU is limited to either a single CPU or four cores.
  • Maximum memory is 1410 MB, regardless of what is provisioned on the machine.
  • The maximum columnstore segment is 352 MB.
  • Maximum memory-optimized data per database is 352 MB.

SolarWinds NTA makes extensive use of columnstore indexing, and the limitations for segment sizes make the Express edition an impractical option. The 10-GB limit is not suitable either, as NTA ingests and stores large volumes of detailed flow data. This causes performance issues and limits key features for NTA storage.