Monday 16 October 2023

Teams Survivable Branch Appliance (SBA) Logging Issue

If you plan on deploying a Teams Survivable Branch Appliance (SBA) for a larger site you need to be aware of the amount of logging that the Teams SBA service will do to disk. The amount of free space on an SBA can be very limited so it’s important to keep an eye on the logs being generated. 

Here’s an example of a Virtual SBA from AudioCodes that only has 40GB of HDD space to begin with:

Based on this limited amount of space you can’t really expect to be doing a massive amount of logging on the server. Before you go into production you need to be ready for how large the log files are going to be.

Here’s an example of the logging folder from a Teams SBA with over 1000 users connected it. You can see that the main SBA log file rolls once and hour and that each file takes up about 30 MB of space:

If you do some math that’s 24 x 30MB per day of logs being generated on an SBA with 1000 users on it. That adds up to 792 MB per day… Now multiple that by how many days the SBA service logs for by default (30 days!). That’s about 23.7GB of log data that will be stored on the SBA with 1000 users. If you’re wondering what happens when the HDD completely fills up; the SBA service can crash and stop operating. Hot tip: you should try and avoid this.

In order to avoid this issue, you need to tune the number of days that the SBA service will store data on the Teams SBA server. This setting is hidden away in the SBA settings file stored here:

  C:\Program Files\Microsoft\Microsoft SBA\sbasettings.json

Within the file there’s a setting called MaxArchiveDays which you will see defaults to 30 days. All you need to do is reduce this to a value that will work for your available HDD space:

  "Sba": {

    "Identity": "",

    "TenantId": "523fsdfa-d630-2331-a231-d17123fdc377c",

    "Logger": {

      "Directory": null,

      "Level": "Info",

      "MaxArchiveDays": 30




Once you edit this setting the service will pick up the change in real time and prune the existing files down to the new number of days. Crisis averted!


The Wrap Up


Be good to your SBA, treat it well, have some empathy for the machine. I hope this saved you a nasty surprise. Cheers!

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