Best Practices When Protecting Virtual Machines Running MSCS

KB Number:



An administrator maintaining VMs running Microsoft Clustering Services (MSCS) may want to know the best practices for protecting these VMs with Zerto Virtual Replication.  This article references a document containing these best practices.

Affected Versions

ZVR 3.1 and greater




Support by Zerto Virtual Replication for virtual machines running MSCS is limited to enterprises only. Cloud service providers offering DR-as-a-Service (DRaaS) or In-Cloud DR (ICDR) cannot offer to protect virtual machines running MSCS using Zerto Virtual Replication.

For enterprises that want to protect virtual machines running MSCS, Zerto Virtual Replication enables protecting these machines as long as the following requirements are met:

  • The virtual machines run Windows Server 2008 and higher.
  • The Microsoft SQL Server database is Microsoft SQL Server 2005 and higher.
  • The cluster is an Active/Passive cluster and a maximum 2 node cluster. Only the primary active preferred node is protected by Zerto Virtual Replication, replicating to a preprovisioned RDM in the recovery site.
  • The secondary node is not protected by Zerto Virtual Replication.
  • All of the Cluster services are configured to be dependent on each other to ensure they all exist on the same node at all times. If cluster services are on different nodes simultaneously, then one of them is going to be always in an inconsistent state.

Note: Replication to a preprovisioned RDM in a vCD environment is not supported. For this reason, the recovery site must be to a vCenter Server.

Based on the above requirements, if your MSCS environment includes any of the following, the virtual machines cannot be protected by Zerto Virtual Replication:

  • Microsoft operating systems earlier than Windows server 2008, for example Windows Server 2003.
  • Microsoft SQL Server earlier than Microsoft SQL Server 2005, for example Microsoft SQL Server 2000.
  • An Active/Active cluster or an Active/Passive cluster with both nodes in the cluster being protected.
  • The target disks are VMDKs of the MSCS disks.
  • In addition, you cannot use Zerto Virtual Replication to protect two virtual machines to the same target RDM nor when using VMDKs as shared cluster disks. Also, you cannot use iSCSI in-guest initiators to access shared cluster disks.

For additional information and specifics regarding how ZVR works with MSCS, refer to the following document:

Best practices When Protecting Virtual Machines Running MSCS

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