Performance Testing; Network vs Storage

 I’m sure we’ll all been there; you are working on a ‘performance issue’ and another technician tells you, “I don’t know what the problem is, ping response time is fast and ping didn’t report any dropped packets.”

I’ve written and spoke about this before, but want to briefly cover my concerns surrounding ping. I will start with a simple statement that I am not ‘anti-ping’ and actually use it quite often. My concern is that I see it used in the wrong scenarios and its operation is widely misunderstood.

Things you should know about Microsoft’s ping command include that they are sent at a 1 second interval, uses ICMP as its protocol and neither option are configurable. Other default settings you can change are default payload size (-l), TTL (-i), disabling resolve to address (-a), setting do not fragment (-f) and forcing to just use IPv4 (-4).

I personally prefer to use hrping (https://www.cfos.de/en/ping/ping.htm) as an alternative to Microsoft’s ping since it has many more options and still a command line tool, even though hrping also provides a GUI interface as well. This utility can send UDP packets, send a ping size ‘sweep’ of various sizes, send ICMP timestamp requests, interval between packets as well as the same options as the Microsoft ping command.

In summary, I use ping to validate or verify if the network and hosts are responding and if there is general packet loss. If the ping test results in no packet loss and response time is acceptable, I test the client or server performance.

If you want to test network performance, nothing beats iperf3 (https://iperf.fr/) but if you want to test the file system, copying a file is the easiest test. I know, this isn’t the same as sending hundreds of transactions, etc. but it’s a great start. In this video I show you how I used a simple Powershell command (Measure-Command) to time how long it took to copy files to/from my server.

In this video, I show you how I used iperf and a power shell command to copy a file (both read/write) on two different shares to identify if the issue is file system or network related.

Microsoft Command line and Wireshark utilities

 

I get quite a few emails expressing frustration and confusion when people try some of the Windows Wireshark command line utilities like tshark, dumpcap and editcap to mention a few.

The main issue is that many times the Wireshark application folder is not in your path. There are many ways to get around it like

- Change drive and directory to the Wireshark application folder from within the command prompt

- The use full application path for the wireshark utility you are trying to run (ie c:\program files\Wireshark\tshark -D)

- Add the Wireshark application fold to your path – which is the one I will cover in the video

I prefer adding Wireshark to the path so I can type the command from any folder, anytime without having to worry about which folder I’m in as well as typing the fill path with the command.

A Quick Guide to Kubernetes Persistent Storage (Gilad David Maayan )

 

What Is Persistent Storage?

Persistent storage, or nonvolatile storage, involves using data storage devices that can retain data after the device is powered off. The Kubernetes architecture initially offered only ephemeral storage volumes that were bound to the lifecycle of containers.

This type of storage works for stateful applications but does not allow you to retain data beyond the scope of the container. Later versions of Kubernetes storage introduced persistent storage volumes that enable you to build stateful applications.

Cabling Problems? 100 Mbps vs 1 GBps

What could possibly go wrong? I plug the cable in, get a link light, ping something and ensure there are no issues; I’m done, right? We’ve all done it a million times right?

I replaced two older switches with ones that support gigabit speeds. Followed the same routine that i mentioned earlier, the lights are green and tested fine with a couple of pings.

The other day I decided to do a Speedtest between two computers that traversed both switches. To my surprise, the speeds were less than 100 Mbps. So, I thought, why not document the troubleshooting steps so I could help others who might encounter the same issue.

Find Your Security Vulnerability Before Hackers Find It For You

 Every Network Has a Security Vulnerability — Where is Yours?

One of the top questions on the minds of network security personnel is "how do I reduce my security risk?" Even for smaller organizations, this is important because every network has a weakness. But do you know where you are the most vulnerable? Wouldn't you like to fix the problem now, before a hacker exploits it?