Articles: Storage

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Disk Response Time

For 10 minutes IOMeter is sending a stream of requests to read and write 512-byte data blocks with a request queue of 1. The total of requests processed by each SSD is much larger than its cache, so we get a sustained response time that doesn’t depend on the SSD’s buffer size.

The SSDs all have very low read response time. The Reactor and the 256GB Performance are somewhat worse than the others, but the difference is negligible at less than 0.1 milliseconds.

The results differ more at writing. The Reactor and the senior Extreme series models are close behind the leading Force whereas the Nova, despite its 128GB capacity, is as slow as the junior Extreme series models. The Performance series performs poorly, the 128GB model having a response time of over 1 millisecond (that would be a fantastic result for an HDD but only a mediocre one for an SSD).

Random Read & Write Patterns

Now we will see how the performance of the drives in random read and write modes depends on the size of the requested data block.

We can note two facts about this random-address reading. First, the Reactor is slower than its opponents on small data blocks (by the way, when looking through the results of this test, you should be aware that hard disk drives are about 50 times slower here). Second, once again (after the OCZ Vertex 2) we see the SandForce being slower than the other controllers on data blocks of 4 KB and smaller.

Here, the results correlate with the write response time of the SSDs with minor exceptions that can be observed in the diagrams. For example, the JMF612-based Reactor prefers very small data blocks, coping just perfectly with them, but slows down on large data blocks, sinking from a leading position to the group of outsiders. We can see the pair of Performance drives with Samsung controllers suffer a similar, if not so dramatic, performance slump.

Take note that the Extreme series drives go in pairs: “large & fast” and “small &… not so fast”. The Nova should belong to the first group with its capacity, but falls into the second one with its performance.

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