Random Read & Write Patterns
Now we’ll see the dependence between the drives’ performance in random read and write modes on the size of the data block size. We will only discuss the processing of small data blocks measured in operations per second. With large data blocks, the performance depends on the drive’s sequential speeds.
Random reading in small data blocks agrees with the results of the response time test. It shows the drives’ standings clearly. When the data block size changes, the speeds also change, but the relative standings remain the same. So, we can once again compliment the Western Digital RE3 and Caviar Black as well as the Hitachi 7K1000.B and E7K1000. The low results of the 3-platter Seagate Barracuda 7200.11 and the lower-still performance of the SV35.3 can be observed with any size of the data chunk.
The standings at random writing are the same as in the response time test, too. But it is interesting to note the performance of the Seagate drives here. First of all, it is the 4-platter Barracuda 7200.11 which cannot cope with writing in very small data blocks (we use 512-byte blocks in the response time test) and has very low speed with them. The 3-platter model from the same series is free from that problem. It just writes small blocks slowly just like the SV35.3. It looks like Seagate’s HDD had problems caching small write requests and the developer solved them by just turning this caching off. It’s time to move on to Database where we may see this thing more clearly.