Articles: Storage

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The next graph shows the dependence between the amount of requests processed by the HDD per second and the size of the data block.

It is clear that the Seagate drives are in the lead when processing data blocks smaller than 64KB. There is a graph of the Barracuda 7200.11 on the diagram but it is mostly covered by the graph of the Barracuda ES.2. The two HDDs have the same look-ahead reading strategy.

The Hitachi drives behave similarly to each other too, but they are slower than the Seagate pair on small data blocks. The Samsung is considerably slower on small blocks but goes ahead on large ones. The HDD from Western Digital takes last place in every mode just as you could expect.

This diagram explains a lot. Here is the root of all the problems: the Barracuda 7200.11 proves to be slow only on 1- and 4-sector data blocks (0.5 and 2 kilobytes). It is not about write verification (if the HDD performed it, there would be a flat stretch at the beginning of the graph). The HDD’s processor seems to lose quite a lot of time doing deferred writing.

Interestingly, the Barracuda ES.2 is free from this problem but it is also far slower than its mate on almost every data block size. The Hitachi drives are the best in this test. The HDD from Western Digital is the slowest.

The following tests are about sequential read and write speeds. The HDD’s ability to adjust its look-ahead reading algorithms to the rate and type of requests is important here.

You can see the Samsung doesn’t feel quite good from the start. As I wrote in the Testbed and Methods section, this HDD had made us change our testbed. When I analyzed the test data, I found this HDD to be very sensitive to the bandwidth of the SATA controller. The result above was recorded when the Samsung was connected to a Promise SATA300 TX4302 controller installed into a PCI-32 slot. If the controller is plugged into a PCI-X slot (and begins to work at 66MHz rather than 33MHz), the Samsung wakes up to show its best!

Having tested all the HDDs on the new platform, I can say that some of them don’t care about the testbed modifications. The HDDs from Hitachi and Western Digital do not come near the controller’s peak bandwidth.

Another fact I found, the HDDs from Samsung and Seagate on the new and old testbed only differed in sequential speed related tests. There was no difference in tests that depended on the amount of requests performed per second.

That’s why I have not yet published the results of the HDDs on the new and old platform in this review yet. But now it’s time to do so.

The next diagram shows the performance of the two HDDs that could not reveal their potential on the old testbed. The HDDs tested on the new testbed are marked with the @66MHz suffix.

The Samsung obviously does much better with the controller seated in the faster slot. On the other hand, its speed is still far from ideal on small data blocks.

The Seagate is also faster on the faster bus, especially on 8 to 32KB data blocks. The difference between the platforms is small on large data blocks – 1.5-2MBps.

The performance drop on the new testbed at 4KB data blocks must be due to the specifics of the Promise controller’s operation in the PCI-X slot. This effect occurs in this test only.

Sequential writing goes next.

The HDD from Western Digital shows its best at writing. Despite its modest physical properties, this HDD says that performance is not all about brute force. It is far ahead of its opponents on small data blocks.

The HDDs from Seagate are in the lead on large blocks. The Samsung is not quite good again. Let’s see if these HDDs are any better on the newer testbed.

Yes, the performance improves just as with sequential reading. However, the performance gain on the faster bus is not enough for the Samsung F1 to beat the Seagate drives.

The test of the drive’s ability to reorder random-address read requests is the last one among our low-level tests. In other words, this test can show us how the HDDs can use NCQ technology. IOMeter is sending a stream of requests to read random-address data blocks. The request queue depth is steadily growing up to 32 requests.

The steeper the beginning of the graph is, the better the drive uses NCQ to improve performance.

Well, that’s a brilliant victory of Seagate’s drives. No other model can even get close to the leaders. The Hitachi drives have a flat stretch at the beginning of the graph just like PATA drives with TCQ have, but go ahead at request queue depths of over 16. The HDD from Western Digital started the test slowly but then almost reached the level of the Hitachi drives. The Samsung never really woke up in this test.

Summing up the low-level tests, I can make three interesting points:

  • The platters of the Western Digital drive are rotating at 5400rpm.
  • The Seagate Barracuda 7200.11 is slow at processing random-address requests to write small data blocks.
  • The Samsung SpinPoint F1 is highly sensitive to the SATA controller’s bandwidth.

Now I will check the drives out in more complex tests starting with multithreaded load.

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