Disk Response Time

In this test IOMeter is sending a stream of requests to read and write 512-byte data blocks with a request queue of 1 for 10 minutes. The total number of requests processed by the HDD is over 60 thousand, so we get a sustained response time that doesn’t depend on the HDD’s buffer size.

Response time at reading is one of the main trumps of flash memory. Even early models of SSDs were far better than 15,000rpm HDDs in this parameter. Intel has managed to improve it threefold. Its SSD has a read response of 0.07 milliseconds in our test. This fantastic result must be due to the fast controller. Take note that the read response is most important for your user experience because it is this parameter, not the sequential speed, that determines the delay when you try to read small files. And this parameter is among the hardest to improve. In fact, there is only one way to reduce the read response of HDDs – to increase the spindle rotation speed. The speed of the read/write heads and of the electronics doesn’t have a big effect on this parameter. You can’t improve it even by uniting HDDs into a RAID array: this can increase the amount of operations per second at high loads as the requests will go to the different disks, but the access time of each specific disk will still depend on the spindle rotation speed of the disks you use.

Well, there is even more progress with the write response of the SSD. Early SSDs had a very high write response, many times higher than that of HDDs, but the write response of the X25-M is very low. We were indeed shocked at such a tremendous progress in this parameter, but it was confirmed throughout our tests (and our method of the response time test doesn’t allow the drive to cheat – it just can’t do anything else with such a large amount of requests). The X25-M not only overtakes but beats the best of HDDs thanks to its multi-channel controller, efficient algorithms and buffer memory!