Every now and then questions about SRM licensing pop-up. As you may know SRM comes in two editions: SRM Standard and SRM Enterprise. The next table outlines the differences between SRM Standard and Enterprise and is taken from VMware KB 2000394:
Another important difference between SRM Standard and Enterprise is the maximum number of virtual machines that can be protected. For SRM Standard this is 75 VMs per site, with SRM Enterprise there’s no license limit. This means that if you have to protect 76 VMs at one site, you are required to have an SRM Enterprise license for at least 76 VMs.
Nevertheless, there’s an interesting licensing options if you’re running an active/active SRM setup. In this setup you have protected virtual machines running at both datacenters, with (as a consequence) also placeholder VMs at both sites. In this configuration you can have a maximum of 150 VMs licensed with the SRM Standard product. The VMware Product Guide provides some additional details on this configuration:
For vCenter Site Recovery Manager Standard Edition, you may use VMware vCenter Site Recovery Manager subject to the following restrictions: (a) protect up to seventy-five (75) Virtual Machines within a physical facility or building; and (b) for each running copy of vCenter Site Recovery Manager Standard Edition, manage up to seventy-five (75) Protected Virtual Machines (“SRM Standard Edition Restriction”). If at any given time, the number of Protected Virtual Machines in subsections (a) or (b) exceeds seventy-five (75), You are required to upgrade all Your VMware vCenter Site Recovery Manager Standard Edition licenses to vCenter Site Recovery Manager Enterprise Edition. Notwithstanding the foregoing, the SRM Standard Edition Restriction shall not apply if a failover of Protected Virtual Machines causes the number of Protected Virtual Machines to exceed the SRM Standard Edition Restriction within a physical facility or building for a reasonable period of time.
This piece of text certainly clears up some things. Yes, with SRM Standard you’re allowed to run 75 VMs per site (facility or building), so with two sites you can run a total of 150 VMs. You’re even allowed to run 150 VMs at one site for a reasonable period of time.
I hope this helps in determining the best way to license SRM in your environment. Always verify your setup with a VMware representative, this article is just for informational purposes!