Thursday, March 26, 2015

Moving EMC VPLEX Witness server to the cloud - vCloud Air

To have a full active-active storage setup with live fail-over in case of a site failure for EMC VPLEX (with e.g. VNX or VMAX below), a Witness server is required. This is a small OVF Linux appliance (based on SLES). The witness server must be placed in a third failure domain, ie a third physical site.

If this is not done, then manual intervention is required to activate remaining site. This is described here (EMC documentation) and here (VMware documentation).

I have seen at multiple clients that a third site is not available and then the Witness server is placed on one of the two sites.

I looked into whether the Witness server can be moved to a cloud provider. Apparently it cannot be moved to Amazon AWS due to a specific kernel parameter set in the appliance (SLES) that doesn't match with the underlying AWS hypervisor, which is based on XenServer (this is what I've been told).

My thought was that the new VMware vCloud Air IaaS solution could be used as it is based on VMware ESXi and the Witness server normally runs on an ESXi host. Contacting EMC both in Denmark and in Sweden did not give a result. They didn't know whether this could be done and the official VPLEX documentation doesn't specify anything in this regard (link above).

However, after a bit of digging I found an EMC whitepaper that describes this exact situation (it is from 2015 and probably quite new)

It is technically possible and supported by EMC. The white paper includes documentation, installation steps, and security details. EMC professional services can assist with install/config if required.

Update 2015.07.22: We have now implemented this successfully in production and it was a fairly painless process.

Link to white paper

It should be ensured that proper monitoring is set up for the Witness server. Connection state can be verified manually in the VPLEX Unisphere interface (see below). Also VPLEX can be configured to send SNMP traps to a monitoring tool for alerting.