The Microsoft Exchange team is an interesting group. For years, it seemed like they didn’t listen to any user feedback about the product. The GUI was way too complicated and automation procedures were difficult because there was not a convenient CLI for the product. When Exchange 2007 came out, even though the GUI lacked a little functionality, the product as a whole was way better and it incorporated a lot of feature requests that Exchange admins have been asking for. Most notably, the LCR, CCR, and SCR features that allow local HA and DR for Exchange with a lot less complexity than past versions.
Now, enter Exchange 2010. Exchange 2010 takes everything that we were introduced to in Exchange 2007 on the availability side (LCR,CCR, SCR) and removes it. Yep, removes it. All the availability features have been merged into one technology called Database Availability Groups (DAGs). DAGs have a really nice feature set on paper…I say on paper because I haven’t really implemented them in practice, but the one deal killer at least for most of our customers is that DAGs REQUIRE Enterprise Edition OS licenses. [more]The reason is that DAGs still depend on pieces of Microsoft Cluster Services. This kinda stinks because in Exchange 2007 you could implement database HA with LCR and DR with SCR and never buy any Enterprise licenses. Like I said, the Exchange team is an interesting group….I wonder if they discussed this and decided...”that’s no big deal…doesn’t everyone have Enterprise volume licensing”.