Disk speed as well as the computing power is the most important value for VPS.
We used the 1k, 10k, 100k, 1M, 10M and 100M blocks For the speed test and tracked all the time with Unix command dd. The reason for such a different block sizes is that the speed varies for the larger and smaller block size. Most of the promo texts show the speed for the larger blocks because the speed for the larger files is usually higher. But in the real traffic most of the files are smaller. So the results of our test are for each file size.
We had to install PHP on a clean CentOS VPS in prior to run the test. Test is build on a script which combine the PHP and dd command. PHP is the only additional software installed.
Script is slightly modified so all the test results are saved in the external MySQL database. Everything is saved at the end of the test of all blocks (1k, 10k, 100k, 1M, 10M and 100M).
Each block is tested 7 times. The best and the worst results are removed and the final result for each block is the average value from the remaining 5 tests. The measurements were executed 2 times per hour using the CRON and on servers in different countries. We couldn’t test all the servers offered by the providers but we did our best to test as much locations as possible. The total number of tests is 3867. According to this the tests are quite accurate and actual to 5th august 2015.
Results for the disk speed test of DigitalOcean and Linode in linear graph. Attached is also the logarithmic graph to compare the speed for the smaller blocks where the difference in MB is smaller.
Comparsion of the writing and reading speed of each block
Average speed for each VPS provider