Seagate Barracuda 7200.8: 400GBs with NCQby Purav Sanghani on April 20, 2005 4:30 PM EST
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Seagate on NCQOur 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.