Seagate on NCQ

Our first look at an NCQ enabled drive was over a year ago with Maxtor's MaXLine III 250GB (NCQ) unit. Though not the highest in capacity at the time, the MaXLine III brought with it not only the NCQ feature, but also the largest buffer that we have seen in a desktop drive to date - 16MB. It outperformed the Hitachi Deskstar 7K400 in our IPEAK business and content creation Winstone 2004, SYSMark 2004 synthetic benchmarks, as well as in real world application performance and came second only to Western Digital's 10,000RPM 74GB Raptor. The unit did not perform as well as we thought that it would in our multitasking portion of our benchmarks, but its overall performance was exceptional.

Since then, we have only seen one other manufacturer implementing the NCQ feature in its drives and that is Seagate Technologies. One reason for this is the lack of support from motherboard chipsets for the feature. At this time, only Intel's and NVIDIA's newest motherboard chipsets support Native Command queuing, which limits the combinations of hardware that can be used. More specifically, boards like Intel's 910, 915, and 925 chipsets with ICH6 (I/O Controller Hub 6), and NVIDIA's newest nForce4 based motherboards, which have the Advanced Host Controller Interface (AHCI), are the only boards that will allow users to enable NCQ for drives with the feature.

How does NCQ work?

Native Command Queuing is a method of reading and writing to the disk, which takes into account the physical location of the list of requested data on the platters themselves. We described how NCQ works in our Maxtor MaXLine III review last year with our analogy containing the errand run between the grocery store, drug store, and mall, but we will again explain the process that an NCQ enabled drive goes through as well as the motive behind implementing such a technology in a desktop drive.

We all know how frustrating it can be to run multiple applications at once only to find that our multitask-capable OS slows to a crawl, especially those that require a large amount of reads and writes to the hard disk drive. Things slow down because as each application makes a request to access the drive, those requests are put into a queue and the drive will get to them on a "first come, first serve" basis. This becomes a problem when we have data scattered all over each platter, and the only way to retrieve this data is to wait for it to queue up; and considering that the list of requests is in a random order, this can take much longer than just a few milliseconds (very long when it comes to computing)!

Now, take your applications running on your OS and throw an NCQ enabled drive in the mix. The function of NCQ is all in the name. Native Command Queuing takes the randomized list of requests in the drive's queue and organizes each request based on the location of the requested data on the disk. For example, we have a 30MB Photoshop CS image on our hard drive, which is broken up into five segments on platter 1. The file is spread out on 5 different tracks and to make things more complicated, they are not tracks 1 through 5, but rather 1, 3, 5, 6, and 8, and each piece of the file is not in order on those tracks. When the application requests the PSD file, it sends to the queue of the hard disk the segments that it requires in order from A through E. To get from file segment A to segment B, the read head must skip from track 1 to track 5 to retrieve the data in that order. The read head must then move back to track 3 to pick up segment C of our 30MB PSD file and so on, and this skipping back and forth between tracks takes more time than it should. A more efficient way to gather the requested data would be to read from track 1, then 3, then 5, 6, and 8 last no matter what file fragment is picked up. The file can then be put together in the drive's cache for delivery. This is what NCQ does. As a file is requested, the NCQ feature organizes the five segments of the 30MB PSD file by their locations on the hard disk drive. After the drive reads the data, it is sent off to the OS. Much more efficient, right?

Of course, an NCQ drive can still operate with the NCQ feature turned off, but it will perform just as any other drive with randomized request lists. As we mentioned earlier, not all motherboard/chipset combinations offer support for NCQ, so those of you with older motherboards may need to pick up a newer Intel ICH6 or nForce4 board with AHCI support along with a new NCQ hard drive to take advantage of this feature. As we run our benchmarks, we will keep tabs on how NCQ helps both the Seagate 7200.8 and Maxtor's DiamondMax 10.

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  • AtaStrumf - Thursday, April 21, 2005 - link

    #29 - I found a similar test that includes a WD Caviar drive and from what I can tell it is not exactly lagging.

    http://www.storagereview.com/articles/200504/20050...
    Reply
  • Calin - Thursday, April 21, 2005 - link

    In "WinBench99" page, you said "The Disk Transfer Rate test reads from the media in a linear fashion from the beginning (inner tracks) to the end (outer tracks)". It's false, the hard drives have the beginning tracks on the outside (well, exterior) of the platters, and the inner drives in the interior part. The reason is that while stationary, the read heads stay outside of the media, and they will reach the outer tracks sooner. Also, on the outer tracks the data density is increased, so the data read and write speed is increased also. Reply
  • emboss - Thursday, April 21, 2005 - link

    I'd say you need to ditch Winbench 99 for transfer tests. It's physically impossible for drives to have the same transfer rate on the inside and outside of the platters. Not to mention that the ONLY drives that showed this behaviour were NCQ drives. I suspect what is happening is that the NCQ reordering is stuffing things up by reading the data out-of-order, and that the reordering process delivers the data in one (or several) burst blocks that do not correspond to the real transfer rate off the platters. Maybe HDTach might return more sensible numbers. Reply
  • Lonyo - Thursday, April 21, 2005 - link

    Are you going to do some more HDD/NCQ testing when we get more dual core CPU's to test in multi-taking situations?
    The recent article on the Pentium D shows the benefits of NCQ combined with a dual core CPU (the single core CPU's didn't really show any improvement), so are you going to go more in depth hopefully soon (after you can publish results of AMD X2 CPU's)?

    http://www.anandtech.com/cpuchipsets/showdoc.aspx?...
    http://www.anandtech.com/cpuchipsets/showdoc.aspx?...
    Reply
  • jm20 - Thursday, April 21, 2005 - link

    How is the 7200.7 120Gb drive louder then a Raptor? My 7200.7 120Gb drive is near SILENT, no where loud as a Raptor. I think your measuring device is off forthe Acoustics test. Reply
  • segagenesis - Thursday, April 21, 2005 - link

    #20 - Thats easy. Ignoring the Raptor they are lagging behind on the consumer front compared to others. Last I checked they still charge a fair amount extra for a drive with a FDB motor. The performance just hasnt been up to par either. The days when the "Special Edition" drives were great are gone.

    Reply
  • Palek - Wednesday, April 20, 2005 - link

    Purav, you did not explain why you chose to test with an nForce chipset over a chipset from intel.

    For one thing, nVidia's ATA controllers/drivers have a fairly poor track record. I still remember the multitude of problems that cropped up when people installed nVidia ATA drivers on their nForce2 motherboards. I run my nForce2-based computer with MS ATA drivers because I am too afraid that the nVidia drivers will wreck my system (that, and ExactAudioCopy does not recognize any optical drives with the nVidia drivers installed). Admittedly, these issues were driver-related, but then nVidia's checkered past does not boost my confidence in their ability to provide an nForce4 driver that actually works according to spec. Maybe we're seeing no boost with NCQ because of poor implementation, who knows. Testing with just one platform will not reveal such issues.

    Also, among other things intel is known for their rock-solid and impressively fast ATA controllers, so an intel chipset would be the obvious platform of choice for testing such new technologies as NCQ.
    Reply
  • erwos - Wednesday, April 20, 2005 - link

    "It's mentioned in the article that all of the 7200.8 drives use a 3x133gb platter configuration."

    This actually isn't true, from what I've read elsewhere. Read the following at StorageReview:
    http://www.storagereview.com/articles/200504/20050...

    It makes a lot more sense than the "leftover space" theorem.

    -Erwos
    Reply
  • quorm - Wednesday, April 20, 2005 - link

    xsilver, the drive is not "guaranteed reliable." The only warranty is that if it breaks within five years, they will repair/replace it. There is a possibility that data can be lost from any portion of the drive. You have no way of knowing whether this additional space, if accessible, would be any less reliable than the rest of the drive. Yes, modifying the drive would probably void the warranty, but I'm wondering if Seagate is selling software-limited, yet physically identical drives at different prices, much like with ATI's 9500/9700. Reply
  • Zar0n - Wednesday, April 20, 2005 - link

    With NCQ on u get worst results than with it off.
    This may be good at servers, but no good at desktop.
    I’ll say its bad implemented but, all drivers seem to suffer.
    So no NCQ for me...
    Reply

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