Concept Explained: Running Multiple vSphere Replication Appliances

Playing with vSphere Replication in my lab recently (following my joyous experiences with my HP MSA P2000 detailed here), I came across a small gotcha that might catch out some of those who (like me) learn stuff by playing with them, whilst reading about the deployment technical aspects alongside.

vSphere Replication in vSphere 5.5 has been enhanced over the v5.0/1 release, to enable multiple replication appliances to be deployed and managed by the same vCenter instance. vSphere 5.5 allows upto 10 replication appliances per vCenter, selectable on configuring a VM for replication or available for auto-selection.

The gotcha comes when registering subsequent appliances to a vCenter after initial replication connection has been established between a remote and a local vCenter.

Concept

When configuring vSphere Replication, a single appliance (listed as ‘Embedded’ in the Web Client) is listed in the vCenter Inventory > vSphere Replication > (vCenter) > Manage > vSphere Replication > Rerplication Servers. Additional servers can be deployed (up to a maximum of 10) using the following model:

vSR-Concept

Note: There is a single ’embedded’ or a master appliance, which maintains the VRMS and an embedded database for the vCenter. This tracks replication for all the VMs for the vCenter instance. Additional appliances registered to the vCenter do not maintain their own databases – instead they are slave or secondary to the embedded or master appliance. (The dependency arrows might not be 100% correct in terms of direct communication, but this is just to demonstrate the principle that secondary appliances don’t maintain their own databases, instead using the embedded DB in the primary or master appliance).

Gotcha!

When deploying a second, third, or fifth appliance to a vCenter, remember:

  • DON’T deploy a second vSphere Replication appliance from the original OVA file downloaded from VMware.
  • DO use the Replication Servers screen in Web Client to register additional appliances to the existing vCenter server.
  • DO use the ‘Add On’ package downloaded alongside the original OVA file from VMware for deployment of additional appliances, not the original OVA file itself.

IF you do deploy a second complete OVA master, and register it with the vCenter Server, this will corrupt the entry in the vCenter Inventory for vSphere Replication, and the connection will need to be removed and reset for the two appliances to connect and communicate for the purposes of replication.

Jeremy loves all things technology! Has been in IT for years, loves Macs (but doesn't preach to others about their virtues), loves virtualization (and does shout about it's virtues), and sometimes skis, bikes and directs amateur plays!

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