Capacity Planning – Yes Transaction Log Space is Critical to Keeping your Databases Healthy and Mounted

I think the reason why it's such a big problem is that DAG's have introduced much more complexity into planning for databases & backups that organizations are not prepared to properly plan out their new Exchange 2010 infrastructure.  you could write an entire book just on DAG planning and backups and Exchange Native Data Protection and some of the most common gotchas that companies need to think about when planning these things (like when and where to turn on CRCL and which copy do you backup if you do need point in time backups).  

I know this stuff is covered under the technet article on understanding backups, restores, & DR; but considering that for a decade or more the question of how to handle log growth was as simple as backup (daily full, or weekly full and incremental's) or just turn on circular logging and hope for the best, it's no wonder that companies are having problems with this.  Now, even when you turn on circular logging on a db copy in a DAG, you can still run into a situation where your log files fill up your space and cause a dismount.  I'd imagine not many people realize that.