Home > EMC, VMware > vMSC on EMC VPLEX


EMC PLEX vMSC (VMware Metro Stretched Cluster) support and certification process. I have complied the following detail on the requirements from both VMware and EMC.


There is no formal process to certify a vMSC installation but as long as the storage infrastructure is supported by EMC, equipment is on the VMware HCL and the following the kb articles are followed, the environment will be supported. Ultimately the configuration defined in the below kb articles was verified by and directly supported by EMC.

VMware kb articles:

vSphere 4.x : Using VPLEX Metro with VMware HA (1026692)

vSphere 5.x : Implementing vSphere Metro Storage Cluster (vMSC) using EMC VPLEX (2007545)

VMware published the following best practices whitepaper


Also Duncan Epping blogged about PDL (permanent device loss) condition:



You need to ensure the attached documents are following as per the following detail.

Attached is the EMC “simple support matrix for VMware vSphere 5.x” and GeoSynchrony 5.1 references the following known issue and therefore patch 2 should be applied or the workaround deployed.

emc299427: VPLEX: Fabric frame drops due to SAN congestion

EMC Recommendations/Best Practices for Cluster cross-connect for VMWare ESXi (docu9765 Technical Notes, page 62)

EMC encourages any customer moving to a VPLEX-Metro to move to ESX 5.0 Update 1 to benefit from all the HA enhancements in ESX 5.0 as well as the APD/PDL handling enhancements provided in update 1

• Applies to vSphere 4.1 and newer and VPLEX Metro Spanned SAN configuration
• HA/DRS cluster is stretched across the sites. This is a single HA/DRS cluster with ESXi hosts at each site
• A single standalone vCenter will manage the HA/DRS cluster
• The vCenter host will be located at the primary datacenter
• The HA/VM /Service console/vMotion networks should use multiple NIC cards on each ESX for redundancy
• The latency limitation of 1ms is applicable to both Ethernet Networks as well as the VPLEX FC WAN networks
• The ESXi servers should use internal disks or local SAN disks for booting. The Distributed Device should not be used as a boot disk
• All ESXi hosts initiators must be registered as ―default‖ type in VPLEX
• VPLEX Witness must be installed at a third location isolating it from failures that could affect VPLEX clusters at either site
• It is recommended to place the VM in the preferred site of the VPLEX distributed volume (that contains the datastore)
• In case of a Storage Volume failure or a BE array failure at one site, the VPLEX will continue to operated with the site that is healthy. Furthermore if a full VPLEX failure or WAN COM failure occurs and the cluster cross-connect is operational then these failures will be transparent to the host
• Create a common storage view for ESX nodes on site 1 on VPLEX cluster-1
• Create a common storage view for ESX nodes on site 2 on VPLEX cluster-2
• All Distributed Devices common to the same set of VMs should be in one consistency group
• All VM‘s associated with one consistency group should be collocated at the same site with the bias set on the consistency group to that site
• If using ESX Native Multi-Pathing (NMP) make sure to use the fixed policy and make sure the path(s) to the local VPLEX is the primary path(s) and the path(s) to the remote VPLEX is only stand-by
• vMSC is support for both non-uniform and uniform (cross-connect)

The following configuration requirements from the above VMware article kb2007545
These requirements must be satisfied to support this configuration:
• The maximum round trip latency on both the IP network and the inter-cluster network between the two VPLEX clusters must not exceed 5 milliseconds round-trip-time for a non-uniform host access configuration and must not exceed 1 millisecond round-trip-time for a uniform host access configuration. The IP network supports the VMware ESXi hosts and the VPLEX Management Console. The interface between two VPLEX clusters can be Fibre Channel or IP.
• The ESXi hosts in both data centers must have a private network on the same IP subnet and broadcast domain.
• Any IP subnet used by the virtual machine that resides on it must be accessible from ESXi hosts in both datacenters. This requirement is important so that clients accessing virtual machines running on ESXi hosts on both sides are able to function smoothly upon any VMware HA triggered virtual machine restart events.
• The data storage locations, including the boot device used by the virtual machines, must be active and accessible from ESXi hosts in both datacenters.
• vCenter Server must be able to connect to ESXi hosts in both datacenters.
• The VMware datastore for the virtual machines running in the ESX Cluster are provisioned on Distributed Virtual Volumes.
• The maximum number of hosts in the HA cluster must not exceed 32 hosts.
• The configuration option auto-resume for VPLEX consistency groups must be set to true.
• The ESXi hosts forming the VMware HA cluster can be distributed on two sites. HA Clusters can start a virtual machine on the surviving ESXi host, and the ESXi host access the Distributed Virtual Volume through storage path at its site.
• VPLEX 5.0 and above and ESXi 5.0 are tested in this configuration with the VPLEX Witness.
For any additional requirement for VPLEX Distributed Virtual Volumes, see the EMC VPLEX best practices document.
VPLEX zoning:
• The front-end zoning should be done in such a manner that an HBA port is zoned to either the local or the remote VPLEX cluster.
• The path policy should be set to FIXED to avoid writes to both legs of the distributed volume by the same host.
emc299427: Workaround and Permanent fixes for VPLEX GeoSynchrony 5.1
• VMware ESX and ESXi 5.x hosts can be configured to NOT send the VAAI-CAW command to the VPLEX. On all ESX and ESXi 5.x hosts connected to the VPLEX, the following actions must be completed to accomplish this.
• The setting is represented by the “HardwareAcceleratedLocking” variable in ESX:

a. Using vSphere client, go to host > Configuration > Software > Advanced Settings > VMFS3
b. Set the HardwareAcceleratedLocking value from 1 to 0. By default this is 1 in ESX or ESXi 5.x environments.
The change of the above settings can be verified by reviewing VMkernel logs at /var/log/vmkernel or /var/log/messages:

cpuN:1234)Config: 297: “HardwareAcceleratedMove” = 1, Old Value: 0, (Status: 0x0)
cpuN:1234)Config: 297: “HardwareAcceleratedInit” = 1, Old Value: 0, (Status: 0x0)
cpuN:1234)Config: 297: “HardwareAcceleratedLocking” = 0, Old Value: 1, (Status: 0x0)
• VPLEX GeoSynchrony 5.1 only utilizes VAAI-CAW [ HardwareAccelaratedLocking ] commands and hence this is the only value that needs to be set to 0.
• The values of HardwareAcceleratedMove and HardwareAcceleratedInit can be either 1 or 0.
Caution! There is an option in VPlexcli to set the ‘caw-enabled’ property under the storage-views context. Do not turn off the Compare and Write feature using the ‘caw-enabled’ property under VPLEX Storage-Views context as this may have unexpected negative consequences.This must not be done from the VPlexcli.
Permanent Fix:
• Apply 5.1 Patch 2

Categories: EMC, VMware
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