Changing the Compression Settings for Export

You can adjust the level of compression that SVS applies when it creates a Virtual Software Archive (VSA). By adjusting this level, you can find a balance between performance and size. Jeremy Hurren shows us how to find the perfect balance.

If you have data that needs a different level of compression, you'll be happy to know there's a way you can change that (either per-layer or machine-wide). A perfect candidate would be my MP3 data layer which holds many gigabytes of data. Since the compression on MP3 files is infinitesimal, I choose to have them simply stored and not compressed at all to speed up the process.

The following setting will set the compression level machine-wide:

HKEY_LOCAL_MACHINE\SYSTEM\Altiris\FSL

CompressionLevel (DWORD) = 0-19 (5 is the default)

To set this for an individual layer, place the value under the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\Altiris\FSL\1

(replace 1 with the layer number)

The meaning of the compression level settings are as follows (all numbers in decimal), with higher numbers representing higher compression (and therefore slower operation):

In my private testing on a layer with 170MB of MP3 files, I saw differences of 15-20% in compression time. The type of data you are compressing will affect this, so it may take a little trial and error to find the settings you like best.

For more information about modifying values in the FSL key, see the tip Auto-Closing Applications Running from a Layer.