There are several ways to check the SD memory cards read and write speeds. The best method I prefer is to use gnome disk utility which gives is completely GUI based and presents the results in the form of graph and average read and write speeds.
STEP 1: INSTALL GNOME DISKS UTILITY
Go to ‘Applications’ and launch ‘Terminal’.
sudo apt-get install gnome-disk-utility
You will have to enter root password to complete the installation.
STEP 2: BENCH MARK SD CARD PERFORMANCE
It’s time now to insert the SD card on which you want to run the benchmark tests. Go to ‘Applications’ and enter ‘Disks’ in the search box. Launch ‘Disks’ application. Alternately, you can launch gnome utility from Terminal using the command the following command line.
In the left pane of the Disks, select the SD card. Then click on a gear icon in the right pane. Select ‘Benchmark…’.
You will have to enter root password to begin the tests. The utility will confirm the sample size, number of samples, and access time. It’s OK to stay with the default values.
Click ‘Start Benchmarking…’
The utility will give readings and graph on the fly including Read/Write rate and access time.