Performance in Sequential Read/Write Operations
This is a simple test, but sometimes it yields surprises. We’ll see how well the drives’ electronics handles processing of data blocks of a varying size. Here are the summed up results in Intel IOMeter Sequential Table.
Since the table includes a lot of same-type devices that differ in the capacity only, we took a few typical results and put them into our diagrams. Reading comes first:
The first notable thing is the lag of all the 7K250 series models from their predecessors on small data blocks. That’s rather a surprising start, isn’t it? By the way, we see a clear trend of the results worsening with each new model. Fortunately, reading in small blocks rather seldom occurs in real applications, and the engineers must have considered this fact when sacrificing the efficiency to… to what? It’s hard to say…
Note the behavior of the 7K250 models with a 2MB buffer – they are stably faster than their own 8MB-buffer mates! Do you remember the supposition we made in the previous section that the latter devices have no forced read look-ahead? Here’s indirect evidence to that. However, their showings are similar overall, so we can say that Hitachi has made a good read look-ahead algorithm.
The red line in the diagram is drawn by the model of 60GB capacity – it is the worst of all. To all appearances, we can dismiss it altogether as we can’t hope it’s going to deliver a good performance in any test.
Sequential writing brings less discouraging results, although we see the same trend here – every new generation of the Vancouvers performs worse. Can it be that the engineers are slowly but steadily replacing the electronics? This is also indirectly proved by the measurements of the response of the electronics to various commands. But why? You may remember that the central controller chip in IBM’s hard disk drives used to be very hot at work, so it’s possible that Hitachi is thus keeping the heat generation low until it masters the production of the new controller chip using a more progressive technology.