How to: Throttle bandwidth used by 3PAR’s Remote Copy Replication

I recently setup a pair of 3PAR’s that are about 1,300 miles apart in distance where one of the tasks included was to setup and configure 3PAR’s Remote Copy functionality to replicate several volumes asynchronously to their DR site.  Even though client was in the process of dialing up the point to point line from 1gb to 10gb.  In the meantime, they did not want to saturate the current 1gb link and potentially contend with other traffic.  Even though they could have setup QOS in the network layer its sometimes easier to just do it in the application, if the vendor adds that feature.

After speaking with @ivaniannaccone and performing some testing I found that this is pretty easy to setup if you are using Remote Copy over IP (RCIP) whereas if you have Remote Copy of Fiber Channel (RCFC) our options are much more limited on the application side.  Let’s take a look at how to accomplish this.

SITE A – 3PAR01
SITE B – 3PAR02

  1. Before running the command, we need to stop the Remote Copy Group in question, this can be performed in either the GUI (IMC/SSMC) or the CLI.
  2. The command value can be specified in units of gigabytes, megabytes, or kilobytes per second.  So, let’s say our goal here is to limit 3PAR’s replication to 200mb/s.
  3. The syntax for the “set remote copy” target commands is as follows: setrcopytarget tput <throughput> <target_name>.  So, let’s open up the 3PAR CLI in Site A and input the following command – “setrcopytarget tput 100mb 3PAR02”
  4. Now, you can go ahead and start the Remote Copy Replication Group and check your bandwidth utilization charts to confirm the changes took effect.

Note – To remove this setting issue the same command but with the value set at “0”.

Now, we can verify that the command has taken effect by checking the bandwidth report below.  As you can see most of the traffic is now under 200mbps whereas before this setting was put in place our reports were showing the link to be hovering around the 800/900mbps range.

I do recommend to use QOS if your network supports it but this is a good quick alternative for environments that don’t have the necessary equipment and/or expertise.

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