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Datastores shared across multiple clusters

Good day

Currently we have multiple v5.5 clusters setup, each with its own sets of datastores that it used.

There was a request to make all datastores visible to all clusters:-


VC1 - Cluster A(16 nodes) - Datastore1-10

VC2 - Cluster B(16 nodes) - Datastore11-20

VC3 - Cluster C(16 nodes) - Datastore21-30

VMware administrator wish to make consolidate all 3 clusters under 1 vcenter and make all datastores visible to one another

VC1    - Cluster A(16 nodes) - Datastore1-30

          - Cluster B(16 nodes) - Datastore1-30

          - Cluster C(16 nodes) - Datastore1-30

the total number of vm hosted is around 1000, total storage assigned is around 300TB

The goal is to allow vm to move freely between clusters should there be an issue with resource or service upgrade.

Is this best practice? I googled around and found some articles mentioned that its NOT best practice to do so but there were not any hard facts backing this statement up.

I am looking for some best practice article to list the pros and cons of such approach

many thanks


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1 Reply

As long as the LUNs are in the same vCenter, there will be no technical issues because of a LUN being seen in more clusters. However, you should pay attention to how many hosts in total can see the same LUN and when you have clusters with many hosts, you could get in to trouble because of queue depth per LUN, but this can also happen within the same cluster when there are too many hosts connected to the same LUN and they are all running a lot of VMs on that LUN.

In other words, technically there is no restriction to have a LUN seen by hosts from more than one cluster, practically if you want to keep the load on the LUNs under control, the cluster is a logical way of make separations.

We have Citrix clusters with hosts that can only see LUNs running Citrix VMs because there is a different quality of storage assigned than for normal production VMs. But our Production Cluster and SQL Cluster (licensing issue), do share the same LUNs.