This new service pack fixes problems described by customers using App-V 4.5 SP1. Still, the issuance of a new service pack for App-V 4.5 may seem somewhat confusing because Microsoft announced App-V 4.6 as part of its Microsoft Desktop Optimization Pack (MDOP) 2010 set of tools back in late February.
By the way, for those using App-V 4.6, Microsoft just published a white paper on using application virtualization with remote desktop services via Windows Server 2008 R2.
A Microsoft FAQ (Word doc download) explains the reason for the backtracking to App-V 4.5 SP2. Microsoft still recommends that customers move to latest App-V 4.6 version, which features application virtualization support for Office 2010. However, some organizations can't make that move. Consequently, Microsoft released App-V 4.5 SP2 to fix some issues on the server side while also providing support for organizations wanting to virtualize Office 2010.
App-V 4.5 SP2 is available from Microsoft's Volume Licensing Service Center here, the Microsoft Download Center here, or Microsoft Update. An evaluation copy can also be accessed via Microsoft's MSDN and TechNet portals. Microsoft plans to include the SP2 version in the "next scheduled MDOP refresh," according to the FAQ.
Microsoft is touting the high availability and "enhanced failover protection" enabled with App-V 4.5 SP2. Those capabilities are supported through SQL mirroring, which also helps in disaster recovery scenarios and allows maintenance tasks to be performed using server recycling. Microsoft recommends separating the management server from the database to optimize this SQL mirroring capability.
Additionally, App-V 4.5 SP2 now allows data replication across geographies. That capability can help when recovering from site-wide failures.
The release notes to App-V 4.5 SP2 are available here. This service pack is considered "cumulative," meaning that users don't have to install SP1 first.
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