This post will be an introduction to VMware Site Recovery Manager (SRM) , VMware vCenter Site Recovery Manager is a business continuity and disaster recovery solution that helps you to plan, test, and run the recovery of virtual machines between a Protected vCenter Server Site and a Recovery vCenter Server Site.This series of posts will include why we need SRM? Architecture, Concepts, Features, Deployment and Configuration of VMware Site Recovery Managers latest version. Before we talk about SRM itself , we must understand why we need it?
WHY SRM?
Disaster Recovery as a whole is something that we need to keep in mind but at the same time hope to never face it in Real life. Disaster as a whole can be Natural Calamities such as earthquakes which could be unpredictable , or a disaster avoidance situation where it could be hurricanes/typhoon/floods/fires etc. and this is only the small percent . Most commonly it is Power cuts , IT Hardware failure and Human error that could be detrimental to a growing business . With all Business slowly but surely moving towards 99.99% of application availability and uptime we must think of an alternative.
Impacts is loss of employee productivity , business growths and opportunities , resulting in loss of revenue.
According to Gartner , 93% of all Business that lose their Data Center for 10 days go Bankrupt within a year.
Another major challenge is that the CAPEX gets very large due to maintenance of another Recovery site, The need to match the Servers, Storage and rest of the infrastructure, even during a recovery of a multi tiered the application , the different administrators are not aware of typical archicture , DB admin has no idea about Outlook admin, and so on with the rest. Hence what to recover first and what do to the following becomes extremely complex and time consuming. To address all of these above issues we have the VMware Site Recovery Manager.
ARCHITECTURE
VMware Site Recovery Manager typically involves two sites that is Protected Sites and Recovery Sites, We must understand these Sites are two different geographical locations on map. Generally as the name suggests Protected Site is the Site where VM’s are protected and they are replicated to a Recovery Site. This Recovery Site can be shared Site for many Protected Sites or a single Recovery Site for every Protected Site. This could also be an Bi-directional Protection where each Site will act as Recovery Site for each other.The Below image shows the Typical topologies that we can consider during the deployment of VMware SRM.
You can use Site Recovery Manager to implement different types of recovery from the protected site to the recovery site.
1) Planned Migration
The orderly migration of virtual machines from the protected site to the recovery site. Planned migration prevents data loss
when migrating workloads in an orderly fashion. For planned migration to succeed, both sites must be running and fully functioning.
2) Disaster Recovery
Similar to planned migration except that disaster recovery does not require that both sites be up and running,
for example if the protected site goes offline unexpectedly.During a disaster recovery operation,
failure of operations on the protected site are reported.
Site Recovery Manager orchestrates the recovery process with the replication mechanisms, to minimize data loss and system down time. At the protected site, Site Recovery Manager shuts down virtual machines cleanly and synchronizes storage, if the protected site is still running. Site Recovery Manager powers on the replicated virtual machines at the recovery site according to a recovery plan.
Pre-Requisites for SRM deployment
Once we have chosen the type of Topology that we are going to incorporate, We must start planning for the SRM deployment with the following vSphere Pre-requisites :
1) Both Protected and Recovery Sites must have its own Datacenter, vCenter, SRM instance and Hardware System requirements.
2) We must always run same versions of SRM at both Protected and Recover Sites.
3) We must also run same versions of vCenter at both the Sites and It would also be better if we had same version of ESXi as well.
4) We must also make sure that our vCenter version is compatible with our SRM version using SRM Compatibility Matrix
5) If we are using Array based replication , then same Array based replication must be present at both Sites.
6) If we are using vSphere Replication , then both Sites must incorporate same versions of vSphere Replication
7) We must make sure that version of vSphere Replication is compatible with version of SRM and vCenter using SRM Compatibility Matrix
Site Recovery Manager Licensing
Once SRM has been deployed, by default it takes the evaluation license for a period of about 60 days. SRM when used as a Standalone product is Per Virtual Machine based licensing. After the evaluation license has been expired the VM’s that are being protected will continue to be protected. However we cannot add any new VM’s to SRM if license has expired. If we use only Recovery, that is we are protecting VM’s only in one direction , then we must add license only to the Protected Site. if we are using Reprotect, that is we are protecting VM’s that have failed over in the reverse direction, then we must add license to both the Sites. While adding more VM’s in the protection group SRM checks for the license and only then allows VM to be added to the protection group.
We will now look at the SRM concepts in the next Part.