Brief backgroud: We have (2) identical Dell R510 servers loaded w/ (10) 1TB 7200 nearline SAS drives and (2) 146GB 10k drives for the OS, approximately 800 mailboxes, less than 100GB of databases. We'll be installing Ex 2010 Enterprise & Windows Server 2008 Enterprise (currently on Ex 2k3). I would like some input from the Experts on the Exchange Server role deployments. I know that I want/need to do DAG for database resiliency. I wasnt involved in the procurement of these servers, but was told that the plan was to have all 3 roles (mailbox, CAS, HT) installed on both boxes. However, isnt there a stipulation that if doing DAG you cannot do CAS on both servers because of the limition of only NLB or Clustering can be installed, not both. In this scenario, I've read that you'd need to acquire a hardware NLB instead of using Windows NLB.
With that said, what are the recommendations from the experts on making the most use of this hardware and getting the best HA/resiliency? Also, what are your thoughts on the RAID scenario for this deployment w/ this current hardware? I'm so used to using 15k scsi drives w/ Exchange, but now am reading a lot of recommendations for these 7200 drives and unusual RAID setups...for example, Dell recommends using these (10) drives to setup either 4 or 5 RAID 1 pairs and putting the logs on the same RAID 1 as the database...all of this is so different, I'm just curious to know how the experts are seeing this deployed in real world examples. Thanks in advance.