We're creating an entirely new Hyper-V virtualized environment on Server 2012 R2. My question is: Can we accomplish high availability WITHOUT using failover clustering?
So, I don't really have anything AGAINST failover clustering, and we will happily use it if it's the right solution for us, but to be honest, we really don't want ANYTHING to happen automatically when it comes to failover. Here's what I mean:
In this new environment, we have architected 2 identical, very capable Hyper-V physical hosts, each of which will run several VMs comprising the equivalent of a scaled-back version of our entire environment. In other words, there is at least a domain controller, multiple web servers, and a (mirrored/HA/AlwaysOn) SQL Server 2012 VM running on each host, along with a few other miscellaneous one-off worker-bee VMs doing things like system monitoring. The SQL Server VM on each host has about 75% of the physical memory resources dedicated to it (for performance reasons). We need pretty much the full horsepower of both machines up and going at all times under normal conditions.
So now, to high availability. The standard approach is to use failover clustering, but I am concerned that if these hosts are clustered, we'll have the equivalent of just 50% hardware capacity going at all times, with full failover in place of course (we are using an iSCSI SAN for storage).
BUT, if these hosts are NOT clustered, and one of them is suddenly switched off, experiences some kind of catastrophic failure, or simply needs to be rebooted while applying WSUS patches, the SQL Server HA will fail over (so all databases will remain up and going on the surviving VM), and the environment would continue functioning at somewhat reduced capacity until the failed host is restarted. With this approach, it seems to me that we would be running at 100% for the most part, and running at 50% or so only in the event of a major failure, rather than running at 50% ALL the time.
Of course, in the event of a catastrophic failure, I'm also thinking that the one-off worker-bee VMs could be replicated to the alternate host so they could be started on the surviving host if needed during a long-term outage.
So basically, I am very interested in the thoughts of others with experience regarding taking this approach to Hyper-V architecture, as it seems as if failover clustering is almost a given when it comes to best practices and high availability. I guess I'm looking for validation on my thinking.
So what do you think? What am I missing or forgetting? What will we LOSE if we go with a NON-clustered high-availability environment as I've described it?
Thanks in advance for your thoughts!