System information

ESXi Host Requirements for Protection of MSCS Virtual Machines
To protect MSCS or fault tolerant virtual machines, the ESXi host machines on which the virtual machines
run must meet certain criteria.
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You must run a fault tolerant virtual machine and its shadow on two separate ESXi Server instances.
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You can run a cluster of MSCS virtual machines in the following possible configurations.
Cluster-in-a-box
The MSCS virtual machines in the cluster run on a single ESXi Server.
You can have a maximum of five MSCS nodes on one ESXi Server.
Cluster-across-boxes
You can spread the MSCS cluster across a maximum of five ESXi Server
instances. You can protect only one virtual machine node of any MSCS
cluster on a single ESXi Server instance. You can have multiple MSCS
node virtual machines running on an ESXi host, as long as they do not
participate in the same MSCS cluster. This configuration requires shared
storage on a Fibre Channel SAN for the quorum disk.
DRS Requirements for Protection of MSCS Virtual Machines
To use DRS on sites that contain MSCS virtual machines, you must configure the DRS rules to allow
Site Recovery Manager to protect the virtual machines. By following the guidelines, you can protect MSCS
virtual machines on sites that run DRS if the placeholder virtual machines are in either a cluster-across-
boxes MSCS deployment or in a cluster-in-a-box MSCS deployment.
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Because vSphere does not support vSphere vMotion for MSCS virtual machines, you must set the VM to
Host DRS rule so that DRS does not perform vMotion on MSCS nodes. Set the VM to Host rule for the
virtual machines on the protected site and for the shadow virtual machines on the recovery site.
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Set the DRS rules on the virtual machines on the protected site before you configure MSCS in the guest
operating systems. Set the DRS rules immediately after you deploy, configure, or power on the virtual
machines.
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Set the DRS rules on the virtual machines on the recovery site immediately after you create a protection
group of MSCS nodes, as soon as the placeholder virtual machines appear on the recovery site.
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DRS rules that you set on the protected site are not transferred to the recovery site after a recovery. For
this reason, you must set the DRS rules on the placeholder virtual machines on the recovery site.
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Do not run a test recovery or a real recovery before you set the DRS rules on the recovery site.
If you do not follow the guidelines on either the protected site or on the recovery site, vSphere vMotion
might move MSCS virtual machines to a configuration that Site Recovery Manager does not support.
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In a cluster-in-a-box deployment on either the protected or recovery site, vSphere vMotion might move
MSCS virtual machines to different ESXi hosts.
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In a cluster-in-a-box deployment on either the protected or recovery site, vSphere vMotion might move
some or all of the MSCS virtual machines to a single ESXi host.
Limitations to Protection and Recovery of Virtual Machines
The protection and recovery by Site Recovery Manager of virtual machines is subject to limitations.
Protection and Recovery of Suspended Virtual Machines
When you suspend a virtual machine, vSphere creates and saves its memory state. When the virtual
machine resumes, vSphere restores the saved memory state to allow the virtual machine to continue without
any disruption to the applications and guest operating systems that it is running.
Chapter 9 Interoperability of Site Recovery Manager with Other Software
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