How to Find Utilization Bottlenecks in Your SAN Fibre Channel Ports

In this brief video we’ll take a look at identifying the root cause of high port utilization on my fiber channel SAN fabric. I’ve got a number of charts here that help me in guiding me through the identification of the culprit.

The easiest way to go here is to look at my port utilization. This is looking at the bi-directional port utilization for all the ports on the SAN fabric. It’s highlighted in red that tells me some exceptions are happening.  If you look at the legend here it’s got the switch port or the switch. WWPN usually would be the switch name but I’ve anonymized those for the sake of this video. You can see though in square brackets I have a number of 0.7 that indicates a pretty high rating, but I know that I’ve got a 0.91 in here somewhere. I’m going to scroll down and look for my 0.91 that is SWIT5. I’m going to drill down to that and I see it’s not the E-ports, but the F-ports are having high utilization.

I’m going to drill down to the F-ports. I can see there is a number of them here but the one I’ll click on, is the one that has the highest port utilization. It’s consistently over 50 percent and up to 70 percent.

It may be okay, but it is having quite a bit of throughput consistently.  It looks like it’s a virtual port based on the actual numbers. Now I’ll just go back a couple screens and I’m going to look at this other switch and its ports: the one that was rated with the 0.7. I see I’ve got this port 00062 that has also a high percentage. We can see that it’s currently running at 2Gb/s, but it’s a maximum data rate at 8Gb.

We could probably lower the utilization on that port just by configuring the port correctly. For some reason one of the ports that is connected here to this port, probably this WWPN on this host, is actually configured at 2Gb instead of a higher number for some reason. The way to resolve this would be to set this particular port from 2 to a higher number if that is possible on that device.