There have been a number of questions recently about SMP-FT on Virtual SAN. The Symmetric Multi-Processing Fault Tolerance (SMP-FT) is a feature that many VMware customers have been waiting for. With the release of vSphere 6.0, the SMP-FT capability finally became available. This release did not include SMP-FT support when the VM was run on VSAN however. With the release of vSphere 6.0U1, which included VSAN 6.1, there is now support for SMP-FT when the VM is run on VSAN.
There are some caveats when it comes to the different VSAN deployment methodologies:
- On standard VSAN deployments, SMP-FT is supported
- On ROBO/2-node VSAN deployments, SMP-FT is supported (announced at VMworld 2015 in Barcelona)
- On stretched cluster VSAN deployments, SMP-FT is not supported. The latency distances (up to 5 msec RTT) are simply too great for fault tolerance
Another common question is whether the remote witness appliance for both stretched cluster and 2-node/ROBO deployments can be protected by SMP-FT on a remote host and remote datastores. While this could work in theory, it has not been tested. The general consensus is that vSphere HA should be enough to protect the witness appliance.
With this in mind, lets see how one would go about configuring SMP-FT on a standard VSAN deployment.
This is quite straight forward. FT is displayed as an option from the VM drop down action menu in vSphere 6.0u1 for VMs residing on VSAN. If any anomalies are detected, these are reported in a pop-up window. Here is an example taken from my lab setup:
Now when FT is turned on, you are prompted for a datastore to place the secondary VM.