We are using IA 2017 SP1 and have many times observed that if the installation path already contains a lot of files, then InstallAnywhere CheckDiskSpace adds the size of existing folders and files to required space calculation. This creates problems for our product installers when we are trying to install Feature packs / Maintenance packs / upgrades to existing products which already have several folders present. For example, if our installed product has 500 MB installed on computer and feature pack installer wants to add 50 MB of files, CheckDiskSpace returns 550 MB space required. As our applications generate large data files, the existing files can often go in several GBs and give wrong value in CheckDiskSpace which then disallows the installation. Switching CHECK_DISK_SPACE variable to OFF reduces the count a small amount but often ends up disallowing installations.
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