When configuring a VSAN cluster, it is recommended to disable heartbeat datastores in your cluster, as this ensures that if only the VSAN network fails, vSphere HA will still restart the VMs on another host in the cluster (more info on why the heartbeat datastore should be disabled can be found in the VSAN Stretched Cluster guide here).
Now, when datastore heartbeats are disabled on your cluster, you may then see the following warning message on your hosts:
![Heartbeat Heartbeat](/uploads/1/1/9/8/119856970/712395358.png)
This is because vSphere HA requires a minimum of two shared datastores between all hosts in a vSphere HA enabled cluster for heartbeat detection (more info at the following VMware KB: https://kb.vmware.com/kb/2004739)
So if the only shared storage available is VSAN, then you may want to remove this warning. To do that:
The Number Of Vsphere Ha Heartbeat Datastores
- The datastore is not used for vSphere HA heartbeat; Check the datastore for requirements Datastore Clusters and Storage DRS. If the datastore is part of a Datastore Cluster then you can simply drag it out of the cluster to remove it. Once outside of the cluster Storage DRS will be disabled since you can’t use SDRS without being part of a cluster.
- The number of vSphere HA heartbeat datastores for this host is 1, whuch is less than requiered:2. In version ESXi 5.0 was introduced heart beating over a datastore, FDM HA agent utilizes the storage subsystem as an alternate communication path. FDM HA agent typically needs 2 paths to communicate with datastore.
Move Vsphere Ha Heartbeat Datastores
- In the vSphere Web Client, right click your cluster and select Settings
- Under vSphere HA go to Edit
- Under Advanced Options add the following Configuration Parameter: das.ignoreInsufficientHbDatastore
- For its value, enter true
- Disable then re-enable HA for your cluster to apply the changes.
![Heartbeat Heartbeat](/uploads/1/1/9/8/119856970/461356196.png)
Of course if you don’t want VMs to fail over to another host in your cluster in the event the VSAN network is unavailable, then you will need to configure another non-VSAN datastore to use for heart beats.
You don't need dedicated Heartbeat datastores. You can just use any of the ones that are connected to all the hosts in your HA cluster. Recommended to use two datastores. In our environment I have selected two. Each one is on a different SAN and all hosts can see each. I believe this new Datastore Heartbeat feature is part of making HA more intelligent and able to make better decisions in the case of the Master HA Host being isolated or split off from other hosts. .vSphere HA uses approximately 3 MB of disk space on each heartbeat datastore, which is negligible for most environments.The vSphere HA datastore heartbeat mechanism adds a negligible overhead on the storage system that has no performance effect on other storage operations.