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”
./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
./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 ?
