Mike Byrd (4/12/2013)
Am helping a client upgrade his servers (currently SS 2005 with Windows 2003 cluster). Talked to Dell sales rep this afternoon and he had not heard of anyone implementing Always On for DR. He said all his sales for SS2012 have been for active/passive cluster.I've attended several SQL Saturday sessions and webinars on Always On, but now are worried that nobody has really implemented it in production. I don't want the client to be on the technology tip by himself, but would like to take advantage of Always On if it really works.
I would appreciate it if anybody could tell me if they have implemented Always On and what pros and cons they have found.
Thanks in advance,
Mike Byrd
Your sales person is either misinformed, speaking only based on knowledge that if people are making SQL Server Cluster they state so to ensure they get "certified" hardware or is straight-up lying to you to get you to buy more expensive "cluster certified" hardware. I have 4 clients that have or are in the process of setting up some form of 2012 "enhanced mirroring" (e.g. Always On) for HA/DR/read-only scale-out (or any combination of those 3). There are some amazingly compelling reasons and benefits, and given that it's foundational underpinnings is database mirroring which has been around since SQL 2005 SP1, it is pretty solid given that technically Always On is a v1+SP1 feature! The one con that I know of is a limitation of single-threading the stuff across and hardening it on secondary - which I have heard means a real-world 50MB/second throughput give or take. I note that that is a LOT of data/transactions and that 99.x% of the installed base will never get even close to that. Well, there is also the cost of SQL 2012 licensing as well as the requirement for a Windows Failover Cluster of all machines involved (including any on a different subnet).
If you would like more information feel free to Private Message me.
Best,
Kevin G. Boles
SQL Server Consultant
SQL MVP 2007-2012
TheSQLGuru on googles mail service