You cannot generate an OAB file that is larger than 2GB in an Exchange Server 2010 environment
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Applies to: Exchange Server 2010 EnterpriseExchange Server 2010 StandardMicrosoft Exchange Server 2010 Service Pack 2
When you try to generate an offline address book (OAB) file that is larger than 2GB in a Microsoft Exchange Server 2010 environment, the generation process fails. Additionally, the following events are logged in the Application log on the Exchange Server 2010 mailbox server:
This issue occurs because the OAB generation process encounters an issue when it tries to calculate the location in the OAB file at which to insert data. The OAB generation process encounters this issue when the extracted OAB file is larger than 2GB.
To resolve this issue, install the following cumulative update:
2661854 Description of Update Rollup 2 for Exchange Server 2010 Service Pack 2
For more information about offline address books, visit the following Microsoft website: