Random Read & Write Patterns
Now we will see the dependence between the drives’ performance in random read and write modes on the size of the processed data block.
We will discuss the results in two ways. For small-size data chunks we will draw graphs showing the dependence of the amount of operations per second on the data chunk size. For large chunks we will compare performance depending on data-transfer rate in megabytes per second. This approach helps us evaluate the disk subsystem’s performance in two typical scenarios: working with small data chunks is typical of databases. The amount of operations per second is more important than sheer speed then. Working with large data blocks is nearly the same as working with small files, and the traditional measurement of speed in megabytes per second becomes more relevant.
- IOMeter: Random Read, operations per second
- IOMeter: Random Read, megabytes per second
- IOMeter: Random Write, operations per second
- IOMeter: Random Write, megabytes per second
Everything is neat and nice at reading. The processing of small and large data blocks by the SSDs depends on their response time and sequential speed, respectively.
When the SSDs are writing data in small chunks, the JMicron-based models are affected by their terrible response time. The difference is huge: the graphs of the SSDs with MLC memory and JMicron controller merge with the X-axis if shown in the same diagram with the graphs of the other SSDs. Take note that the Transcend, for all its theoretical writing capabilities in the way of SLC memory, does not differ from the other JMicron-based products. Alas, nothing can be done with the controller’s algorithms here. Frankly speaking, the Corsair P128 isn’t much better: it cannot compete with the SSDs based on Intel’s and Indilinx’s controllers at writing small data chunks.
Comparing the X25-M and the X128, Intel’s controller is faster with very small data blocks but loses its advantage quickly as the data blocks grow larger, eventually falling behind the Indilinx-based Corsair.
As a result, the X128 becomes an unrivalled leader of the test on large data blocks. Take note that the Corsair P128 overtakes and outperforms the X25-M on very large data blocks as it has a higher speed of linear writing. The Transcend’s advantage shows up finally, yet this SSD is still inferior to the products based on other controllers.