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Defragmentation with NCQ

Next we tested each HDD once again, this time with enabled NCQ, i.e. with AHCI support enabled in the mainboard BIOS. I would like to point out specifically, that we don’t claim NCQ support should affect defragmentation speed: everything depends on the defragmentation algorithms implementation. However, enabling NCQ may affect the results (and sometimes quite significantly), so we should absolutely test the hard disk drives in question with this option enabled.

You can see very clearly that the positioning of the testing participants on the chart has changed. Just like during the tests with the built in Windows XP defragmentation tool, Samsung HD501LJ became the winner having ousted Hitachi HDD from that leading position. 500GB Seagate drives that used to be in the third and fifth spots, now require much more time and hence have moved down closer towards the middle of the list. The outsiders are again the same: two old Maxtor drives and WD5000AAKS.

In general, the conclusions we have made in the previous article remain the same here, although the overall results chart has been shuffled a little bit: the HDDs seem to have changed their positions in families.

Let’s introduce an auxiliary Delta parameter that equals the difference between defragmentation times obtained without AHCI activation (with NCQ disabled) and with it (with NCQ enabled):

The results are pretty ambiguous. On the one hand, the difference in defragmentation times during defragmentation with PerfectDisk with or without NCQ is too small for most hard disk drives: it is about the same half a minute that we saw in the previous test session. However, some hard drives go so far beyond these limits that we can no longer explain it by the deviating results.

At first, let’s talk about those hard drives where the Delta is a positive value, i.e. defragmentation with enabled AHCI went on faster than without it. Hitachi HDT725050VLA360 HDD with 750GB storage capacity has improved its results quite significantly: by more than 3 minutes, which pushed it about one third of the list up. All three new leaders have also performed very well, especially Samsung HD501LJ, which performed the tests 43 seconds faster.

Now a few words about those testing participants that were harmed by enabled AHCI. Seagate ST3500630AS and ST3500630NS are the first ones on the list here. "Regular" and server modification of these 500GB HDDs performed 4 and 2 minutes slower, correspondingly. Strange as it might seem, the second Hitachi HDD, HDS721075KLA330, has also performed slower: its result is 52 seconds longer.

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