Partial VM Replication in SRM

I’ve been working with SRM a long time, but here’s a situation I honestly have never been asked about: Can you replicate only some vmdks of a VM? Why yes you can, and it has nothing to do with changing parameters in the SRDF SRA (which I am sure is a relief). This is a capability of SRM. There isn’t much to the functionality so I’ll try to be brief in words and then show a few demos.

I suppose we should start with the why do this at all. There are a few reasons you may not want to replicate a disk, e.g., a Windows page file that is on its own drive, the temp disk for a database like MSSQL or Oracle, etc. You get the idea. As I say, however, the vast majority of customers don’t want the hassle involved in customizing VMs in SRM, but if you have limited bandwidth for replication and use lots of temp space, this is a good way to reduce replication traffic. On to the how…

Environment

I’m going to use a simple environment for this. There’s no need to talk about the application but for the sake of argument let’s call the disk a page file. My environment is a single VM, SRM_SYNC_3, which has two vmdks in two different datastores:

  • SRM_SYNC_3
  • ORA_dsib0242_0243_RAC

Only one of these datastores is replicated which we can see here in SRM:

I think that’s good for the setup, I’ll use some demos for the rest. No callouts in these as it’s easy enough to follow along.

Protection Group & Recovery Plan

This demo will walk through creating the protection group and recovery plan. You’ll see that SRM immediately recognizes that ORA_dsib0242_0243_RAC is not replicated and produces an error. Then as part of the protection group creation the non-replicated vmdk will be detached from the VM from within SRM by configuring protection for the VM.

Testfailover

This will run the recovery plan and when complete add back a vmdk for the page file.

Cleanup

I included the cleanup just to demonstrate that adding a disk does not cause any issues during the cleanup process.

I can think of a bunch of caveats here depending on the application. For example, if you are not replicating the temp disk of a database, you’ll want to control the VM startup on the recovery site . That might mean not starting the VM or perhaps scripting it to add the disk back during startup. Anyway a little trial and error is bound to get you there.

Advertisement

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Website Powered by WordPress.com.

Up ↑

%d bloggers like this: