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Hardware Western Digital Launches 750GB Enterprise-Class SATA HDD
Brandon Hill (Blog) - July 19, 2007 10:38 AM

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11 comment(s) - last by TomZ.. on Jul 19 at 5:10 PM

Western Digital's new HDD features a MTBF of 1.2 million hours

Western Digital has stepped up its efforts in the enterprise market with the release of the WD RE2 (RAID Edition) 750GB hard drive. The new drive features a 3.0Gb/s SATA interface and 16MB of cache onboard.

The drive also boasts a MTBF of 1.2 million hours which is sufficient for its use in email, file and web servers. The new drive also features SecurePark technology for shock prevention, StableTrac for resistance to vibrations and IntelliSeek which reduces power usage by up to 60 percent compared to standard HDDs.

"WD has continued to leverage its extensive experience from previous RAID Edition drives, to develop a hard drive perfectly suited for a variety of high-capacity enterprise applications," said Western Digital VP and GM of enterprise storage Tom McDorman. "These drives demand high capacity, reliability, performance and advanced features," said Tom McDorman, WD's vice president and general manager of enterprise storage."

Western Digital's WD RE2 750GB (WD7500AYYS) HDD will ship later this month at a suggested retail price of $265 USD. The drive will be backed by Western Digital’s 5-year warranty.

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MTBF

By Spivonious on 7/19/2007 11:17:57 AM , Rating: 1

Are my calculations wrong, or does the MTBF of these drives come out to over 130 years of constant use? That's essentially saying the drives will never fail under normal use.

RE: MTBF

By TomZ on 7/19/2007 11:25:59 AM , Rating: 5

MTBF doesn't mean that the average lifetime of a unit will equal that number of hours. Here's what MTBF really means:

http://en.wikipedia.org/wiki/Failure_rate

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RE: MTBF

By rdeegvainl on 7/19/07, Rating: -1

RE: MTBF

By phattyboombatty on 7/19/2007 11:59:16 AM , Rating: 2

It's useful for comparing drives from the same manufacturer if that manufacturer uses the identical process every time for coming up with MTBF.

MTBF doesn't really tell you anything about how long your drive will last. Rather, its useful for telling you how likely you will get a failure in the first couple of months (i.e. the odds of getting a "lemon").

An example of how WD may have come up with the 1.2M hours is the following:

Take 1000 drives and run them continuously for 8,500 hours (a little less than a year). Suppose you get 7 failures from those drives during that time frame. Thats 7 / (8500 * 1000) = 0.00000082. The MTBF is thus 1 / 0.00000082 = 1220000 hours (numbers are rounded off).

In that above example, the test lets you know a little something about how likely your drive will fail in the first year, but not really anything about how the drives will perform after the first year. There is no reason why the drives can't all of a sudden have huge failure rates after the first year of operation. I highly doubt any of the manufacturers use time periods greater than one or two months to conduct these tests, and as you said the results are easily skewed by adding more drives and decreasing the testing time. You can get to the point where you test 1,000,000 drives for one hour each, and get huge MTBF times.

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RE: MTBF

By TomZ on 7/19/2007 12:45:21 PM , Rating: 3

In my opinion, the manufacturer's best estimate at drive reliability is already built into the length of the factory warranty period. Careful calculations are done to estimate the total warranty cost, and of course longer warranties on less reliable products will end up costing a lot of money.

There are probably other factors that enter into the length of warranty, but I'm sure that the expected reliabilty is a pretty important part.

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RE: MTBF

By kkwst2 on 7/19/07, Rating: 0

RE: MTBF

By masher2

(blog) on 7/19/2007 1:26:14 PM , Rating: 3

The best way to think of MTBF is that it indicates the chance of a drive failing before the end of its service life.

After that period (usually in the range of 5 years), the MTBF no longer applies.

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RE: MTBF

By TomZ on 7/19/2007 2:42:34 PM , Rating: 2

That's kind of fuzzy, and maybe even circular, isn't it? I mean, people are really trying to evaluate what the actual service life would be. A more useful measure that HDD manufacturers could give would be expected average useful life, although I'll admit that's not practical. But the warranty length is possibly similar to that. Your thoughts?

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RE: MTBF

By masher2

(blog) on 7/19/2007 4:35:18 PM , Rating: 2

Perhaps thats what people may be wanting, but the MTBF rating bears no relationship to service life. Its a failure estimation within the first year of operation only.

Interestingly enough, normally the failure rate will actually decline a bit during subsequent years, and will only begin rising once wearout mechanisms begin to intrude--the standard bathtub curve, . MTBF covers random failures during the middle segment of this curve-- infant mortality dropouts are assumed to be caught during pre-consumer testing, and wearout failures are likewise beyond its scope.

The warranty period doesn't really bear any relationship to either the service life or the MTBF. If you doubt this, consider that not long ago, several drive manufacturers dropped their warranty period to a year, then most raised it again to 3 or even 5 years. Surely the actual reliability of the drives themselves were not varying by such extreme amounts. The warranty period is more determined by marketing and product placement than anything else. Remember that, by pricing a drive high enough, a manufacturer could conceivably offer a 20 year warranty, using the extra cost to replace failed drives three or even four times per unit.

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RE: MTBF

By TomZ on 7/19/2007 5:10:58 PM , Rating: 2

Good points, but pardon me why I go ship one of my Raptors back to WDC for warranty exchange. The thing's only a year old.

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These drives are a ling time coming.

By iFX on 7/19/2007 10:45:56 AM , Rating: 3

/borat on

Essss niiiice! Hiigh Fiveee!

/borat off.

I can't wait to get my hands on some of these. I will be able to double my storage space in my arrays overnight! :)

GO WD!