I have had this question multiple times by now so I figured I would write a short blog post about it. The question is if you can share datastores across clusters with vSphere 5.0 and HA enabled. This question comes from the fact that HA has a new feature called “datastore heartbeating” and uses the datastore as a communication mechanism.
The answer is short and sweet: Yes.
For each cluster a folder is created. The folder structure is as follows:
/<root of datastore>/.vSphere-HA/<cluster-specific-directory>/
The “cluster specific directory” is based on the uuid of the vCenter Server, the MoID of the cluster, a random 8 char string and the name of the host running vCenter Server. So even if you use dozens of vCenter Servers there is no need to worry.
Each folder contains the files HA needs/uses as shown in the screenshot below. So no need to worry around sharing of datastores across clusters. Frank also wrote an article about this from a Storage DRS perspective. Make sure you read it!
PS: all these details can be found in our Clustering Deepdive book… find it on Amazon.
So, you are saying technically it’s possible to share datastores accross clusters? Just trying to get a little more clarification as in your deep dive you state that it’s recommended to mask on a cluster basis due to admin complexities. I assume the complexitites come with telling HA exactly which datastores to use for heartbeating (ie, instruction to only use cluster datastores if more datastores are shared accross clusters). Thank you.
Adam Stone says
I have an enterprise customer that is sharing Datastores between a 4.1 cluster and a 5.1 cluster. This setup was meant to be for an immediate migration, but the migration has been delayed and they have been running in this configuration for many months. There was normal SAN event (zoning) and storage event (masking) and the hosts lost access to one of the LUNs. As we are doing an RCA the customer is asking “Is our configuration supported?” So, we know the configuration works, but do you know if this configuration is specifically supported?
Thank you so much for all the time you put into all this. The industry couldn’t live without you!
Duncan Epping says
As long as the datastore is formatted with VMFS-3 or is an NFS datastore then this is fully supported!
aaaand I just found out the customer is not sharing between 2 cluster but between 3 clusters! 2 x 4.1 and 1 x 5.1 cluster. Same answer, or would you see problems there?