What version of DA? https://www.veritas.com/support/en_US/article.000086947.html
In Microsoft Outlook 2002 and previous versions the maximum allowed size for a PST file was set at 2GB. A certain amount of corruption protection has been implemented and PST files created as part of the DA export process are limited to a maximum size of 1.5GB. In post Outlook 2002 versions the PST format changed from ANSI to Unicode and subsequently the maximum allowable file size for a Unicode PST file is set to 20GB. (This can be increased to 50GB via a registry key).
When exporting data from DA to a Unicode PST there is still a coded limit of 1.5GB and there is currently no way for a DA export to be split into larger PST file sizes.
This issue has been addressed in the following release:
Enterprise Vault 10.0.4 Cumulative Hotfix 3 Release
http://www.veritas.com/docs/000020890
Enterprise Vault 11.0 0 Release Details
http://www.veritas.com/docs/000004151
