Just Another IT Blog

It's time to share some of my experiences, crazy ideas, tips and tricks !!!

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There’s a common question that always pop up when I’m doing Disaster Recovery projects.
What amount of bandwidth would be required for replication ?

It’s a fair question, but it’s hard to estimate it without proper tools or data in place !!!

The majority of storage vendor have tools that monitor their appliances and can tell you the amount of data that would need to be replicated during a period of time.

But what about if you want to use host base replication (vSphere Replication) or you don’t have those tools in place ?!?

In general, you would define your RPO and estimate the amount of data changed on the servers you want to protect (that’s the hard part). You could use the disk metrics provided by vSphere to estimate that.

Luckily, there’s a FLING that can do all this calculation for you, it’s called vSphere Replication Capacity Planning Appliance.

Since it’s an appliance you just have to download the OVF and deploy it on your environment as you always do with appliances.
OBS: this tool is not meant to work with vSphere Replication, if you already have vR deployed on your environment first remove it.

There’s one requirement not documented, to power on the appliance it will check for an IP Pool associated with it’s Portgroup, if there’s none, power on will fail with the error: Cannot initialize property vami.netmask0 has no associate network protocol profile.

Once it's up..first thing is to access the appliance portal for some basic configuration.

Address: https://"appliance_IP":5480
User: root
Password: vmware

Now we need to start the replication on the VMs so you can measure it’s change rates.
OBS: In fact it does not replicate any data, it’s just a simulation.

Login through SSH into the appliance and run the following command to enable the replication monitoring: all the commands should be run under  /opt/vmware/hbrtraffic/bin

To enable replication run: 
./configureReplication --vc=”vcenter” --vcuser=”username” --vcpass=”password” --lwd=”appliance_ ip” --vmname=”VM_name” --rpo=”mins”

If the command is fine you will see a message: Enable replication for vm

Also you will see a task on vCenter

OBS: remember it’s a FLING so, it has not been exhaustedly tested, and might not be able to handle hundreds of VMs, so be nice with it…test just a few VMs at a time.
In my case to every VM I added I needed to reboot the appliance in order to add the next one  : (

Leave the appliance collecting the data for some cycles of RPO.
Then, you can go to the Graphs page and check the results:

Address: https://"appliance_IP":5480/vr-graphs/

Just click on the VM you want to check it’s data.

There’s its nice graph with the information you capture for the period.
You can look for past 4 hours average, daily, monthly… my favortie metric is delta size average.

WOW amazing……

Just one bad thing…there’s no graph that sum all the VMs collected, you will be have to sum that by yourself.

Once you are done monitoring, don’t forget to disable the replication running the following command:

To disable replication run: 
./configureReplication --vc=”vcenter” --vcuser=”username” --vcpass=”password” --lwd=”appliance_ ip” --vmname=”VM_name” --remove

Again, if the command is fine you will see a message: Disable replication of vm

 And a message on vCenter as well

 One last tip....
If you do have all the data about your VMs and how much it’s changed over time, you can just use vSphere Replication Calculator.

I bet you are now more prepared to make your estimated bandwidth needs, right ?

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