K.3 Setup

The iPerf tool runs in either server mode or client mode.

The basic usage syntax for iperf server mode is:

iperf -s -w <win_size>

The basic usage syntax for iperf client mode is:

iperf -c <server_ip> -w <win_size>

You can specify units such as K (kilobytes) or M (megabytes) in the value for the -w option. For example: 1.3M or 1300K.

NOTE:Linux automatically doubles the requested TCP buffer size. If you use iperf on a Linux server, the win_size value for the -w option should be only 1/2 of the desired value (that is, <win_size>/2). Otherwise, you will inadvertently test with a buffer size that is twice the desired value.

Our intent is to measure and tune the network between a source and target workload. In many cases, these can be the actual source and targets in use. It is possible to complete the testing using a different workload for either source or target, provided that the substitute has the same network characteristics as the original, such as NIC, network connection, and so on.

NOTE:Ensure that you are not testing the throughput from the PlateSpin server to either the source or the target, as this traffic is minimal, and does not represent the traffic that occurs during a migration or replication.

While it is possible to use a live workload (either Windows or Linux) as the target/iperf server, the following steps provide the environment most similar to what happens at migration/replication time, and is strongly recommended.

To set up and run iperf on the target:

Boot the target workload using the LRD.
In the LRD console, use the helper terminal (accessible via Alt-F2) to do the following:
1. Set up networking using option 5.
2. Mount the CD media using option 6.
In the LRD console, switch to the debug terminal (accessible via Alt-F7) to go to the location of the iPerf tool:
```
cd /mnt/cdrom/LRDTools/iperf_2.0.X/linux
```
Run the iPerf tool in server mode. Enter
```
./iperf -s -w <win_size>
```
NOTE:For a Linux target, remember that the TCP window size you specify for the -w option should be half of the desired value.

To set up and run iperf on the source:

Mount the LRD ISO by using software or physical media.
Open a command prompt (Windows) or terminal (Linux) and go to the location of the iPerf tool:
```
cd <media>/LRDTools/iperf_2.0.X/
```
As determined by the source operating system, go to the windows or linux subdirectory:
```
cd windows

-OR-

cd linux
```
Run the iPerf tool in client mode. Enter
```
iperf -c <target_ip> -w <win_size>
```
NOTE:For a Linux source, remember that the TCP window size you specify for the -w option should be half of the desired value.

NOTE:You can download and use iperf3 for the calculations, which is helpful in certain scenarios where iperf2 is unable to generate useful throughput numbers. Although the command syntax and output from iperf3 differs slightly, it should be fairly straightforward to adapt and interpret the newer output, if necessary.