I was just reading up on VMTN and noticed this great topic. For some reason there are a lot of people that don’t see the difference between HA and SRM. I suggest reading the full topic and especially Jay Judkowitz’s replies and Smoggy’s reply, both are Subject Matter Experts on SRM and explained the topic starter what the differences are and when to use it. Here’s an outtake of the discussion which captures the essence of the answer in my opinion:
- With SRM, you get a much more well defined failover.
- The VMs start in a specified order
- You can set some VMs to be started serially with others starting in parallel
- You can designate VMs at the recovery site to suspend to make room for recovery VMs
- You can have callout scripts and predefined breakpoints to make sure that critical non-VMware activity is done at the right time and place
- You can set the resource pool at the remote site (with the same size or different as the source resource pool) so that you get a predictable and defined QOS on CPU and memory
- Once you have that well defined failover plan, you can test it and audit the results
- Testing will automatically snap the recovery LUNs so you can power on the recovery VMs without interrupting replication
- You can specify a test network at the second site that SRM will automatically put the recovery VMs on during a test so that they do not interfere with the running VMs
- You can therefore do non-disruptive DR testing any time without warning. The recovery plan executes the same as for failover, but in a “test bubble” where storage and network IO are safely segregated away from production work.
- There is a test results page for the recovery plan which lists all test runs, how long they took and how successful they were. From this page, you can drill down to each test run and see exactly what steps succeeded and failed and how long they took to run.
- With the history page, you can grade your organization over time. With the detailed reports, you can troubleshoot specific runs.
I suggest that if you’re looking into Business Continuity / Disaster Recovery and you’ve got questiosn on what/where/when/how with SRM you visit the VMTN forums… these guys really know what they are talking about and can really help you understanding what BC/DR is about.
