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 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.

• IOMeter: Random Read, operations per second
• IOMeter: Random Read, MBps
• IOMeter: Random Write: operations per second
• IOMeter: Random Write, MBps

Extraordinary things put aside, the results of this group of tests can be predicted from the previously gathered data: the response time is the crucial factor for small data blocks, and the sequential speed is for large data blocks. This is what we see here except that the Seagate Barracuda XT falls behind the 7200rpm WD drives when writing large data blocks on both controllers. The Hitachi 7K2000 looks very good for a HDD with lower-density platters.