Hard Drive Speed: What manufacturers don't want you to know

[Big Booger]

HARD-DRIVE SPEEDS
Eliot from Moreno Valley, California, called on the TechTV Netcam
Network asking about drive interface speeds.

There's no real difference between ATA/100 and ATA/133. And there's not much difference between ATA/33 and ATA/133. These "UltraDMA" modes support faster transfer rates in something called burst mode.

ATA/33 can transfer 33 MBps of data, but only for an instant. We're really only talking about the top transfer speed from the hard drive's cache to your system's memory.

On most drives the hard-drive cache totals a meager 2MB to 8MB. Yes, 133 MBps is a lot faster, but only until the cache is emptied. And no hard drive can continue to spit out data that fast.

There are only two numbers that matter to you in hard-drive
performance:
average seek time and sustained throughput speed.

+ Average seek time, measured in milliseconds, is how long it takes, on average, for the drive's read head to get to the data on the platter.
Today's top IDE drives deliver seek times of under 10 milliseconds.

+ Sustained throughput is harder to measure and most drive
manufacturers don't offer that spec.

Manufacturers talk about rotational speeds and areal density,
http://www.webopedia.com/TERM/A/areal_density.html
till they're blue in the face, but these numbers are only part of the drive speed story.

To get the full picture, you'll have to read the reviews and look at
benchmark numbers. StorageReview.com, http://www.storagereview.com/ has numbers on most current drives. Today's fastest IDE drives are capable of around 60 MBps sustained throughput, even if they advertise 133 MBps in burst mode.

Can you put an ATA/133 drive on an ATA/100 controller? You bet. All UDMA drives are downward-compatible with older controllers. For day-to-day use you won't notice any speed difference, either.

From the TechTV.com newsletter.

[FastGame]

I knew it....another Hype trap :(

Glad I never fell for this one :rolleyes: ok that was awhile back when I didn't know better... :p

Time too go to the real deal, SATA 150 :eek:

[Big Booger]

SATA 150 will soon be doubled so hold your horses :D

hehehe

[Conan]

Well I'm not one to believe everything said by TechTV. This one I think you would have to take with a grain of salt. I'm sure some drive benchmarks would disprove this. I can believe the "no significant difference" between ATA 100 and 133 drives but ATA 33 to 133! :eek:

[cash_site]

this isnt like AMD and PR ratings XP2000 at 1600Ghz, buh!!

So, SATA is doubling... interesting ;)

that upgrade will wait... moohaaha. :cool:

[Big Booger]

Interface speed: Here's where the hype goes over the top. EIDE drives typically come with ATA/100 (also known as Ultra DMA100) interfaces, which handle data rates up to 100MB per second. The interface speed is the same as the external transfer rate (also known as the burst rate), which refers to the top speed at which data can be transferred between the hard drive's cache and your computer. The bottom line: a hard drive platter can't pump data at anywhere near 100MB per second, generally maxing out at less than half that throughput. This hasn't stopped Maxtor from introducing the ATA/133 standard, which requires a special card to raise the interface speed by a third. When we tested the same drive at ATA/133 and ATA/100 speeds, the benchmark results differed by less than 1 percent, within the margin of error.

Could the moral of this story be more obvious? Hard-drive speed hardly matters for desktop buyers. If you're picky, you might choose a 7,200rpm drive over a 5,400rpm drive if the two cost about the same (which is possible, given the inconsistencies in hard-drive retail pricing). Otherwise, focus your attention on getting more gigabytes for your dollar.


have a read at that article from Cnet.com
:D