Hitachi Deskstar 7K2000 2 TB?

Silencing hard drives, optical drives and other storage devices

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Hezu
Posts: 38
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Location: Finland

Hitachi Deskstar 7K2000 2 TB?

Post by Hezu » Wed Nov 25, 2009 10:33 am

I noticed one shop is selling Hitachi Deskstar 7K2000 2 TB for quite reasonable price (~30 € less than the WD GP or Seagate LP in 2 TB size). I tried searching for more information on the Internet but found quite little information. So, has anyone yet any experience with these hard drives?

whiic
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Location: Finland

Post by whiic » Wed Nov 25, 2009 5:21 pm

Just curious: which store? Since usually Hitachi HDDs have cost extra here in Finland.

I'm not in a hurry to expand my capacity (just swapped a dead 1TB Greenpower to 2TB Greenpower so I'll be happy with my capacity for a while) and I know for sure that 5-platter 7200rpm certainly cannot be comparable to 2TB GPs so it's just a matter of curiousity to me.

However 7K2000 isn't necessarily a complete disaster. I've read surprizingly positive review of 7K1000. I own a 5-platter 7K400 which isn't that much more horrible than 3-platter counterparts from other manufacturers. Sure, it has more volume, but at least it's smooth and non-tonal... and I've heard there's been further improvement even though the flagships from Hitachi still come out in 5-platter construction.

At least I assume it's 5-platter, considering 1-platter 7K1000.C consumes 3.6W and 2-platter 4.4 watts, the 7K2000 consumes 7.7 watts so the jump is so significant it most likely is not 4-platter. It's still probably the meanest 2-terabyter around even though it uses 400GB instead of 500GB platters. Hitachi has typically used lower density to obtain better real life performance (shorter head stabilizing time after a seek because of lower track density => better random access time). Plus the superior caching algorithms. Aside from WD Black Edition, there really is no competition to Hitachi drives. Samsung is relatively close, Seagate falls way behind the rest.

But I don't really have any actual data from 7K2000, just educated guessing based on previous 5-star flagships and benchmarks from sites like StorageReview (which is probably one of the best sites for benchmarks that manage to simulate real use, along with a Russian site called iXBT (there's English iXBT Labs and xbitlabs, but I don't know their relation to original iXBT. The don't seem to be translated mirrors...). Unfortunately neither is actively reviewing HDDs anymore.

If you want a HDD for performance critical environment and don't care that much about noise, or have a home server stuck into a different room and don't care about higher power consumption of Hitachi drive, it's worth considering. Despite their construction, they aren't as horrible as one could think they are. But they aren't for silent computing and even making them decently quiet might require decoupling, sandwiching, enclosing (for example: Scythe Quiet Drive). If you use commercial quietening products, the 30 eur cheaper price will likely be nullified or exceeded. If you do DIY... then it'd remain cheaper. And you'd get better performance out of it (but 5400rpm WD or 5900rpm Seagate Low-power are probably "good enough" for typical use).

From the low-rpm models, I'd prefer WD over Seagate due to reviews here on SPCR. While they haven't compared 2TB WD to 2TB Seagate, I'd still conclude that WD is more predictable in it's noise output and likely better than Seagate.

____


EDIT:
Maybe it was this store:
http://www.verkkokauppa.com/main.php?pa ... I&cat4=2TB

It's the place I bought my WD20EADS recently. Even if I had postponed the purchase, I still probably would have saved the 30 eur due to 2 week delivery time and higher noise output inherent to more platters and higher spindle speed. My computer is quiet enough to notice any added 7200rpm drive.

EDIT2:
I meant "Even if I had postponed the purchase, I still probably would NOT have saved the 30 eur due to 2 week delivery time and higher noise..."
Last edited by whiic on Sat Dec 05, 2009 11:28 pm, edited 1 time in total.

Tamas
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Location: Budapest, Hungary

Re: Hitachi Deskstar 7K2000 2 TB?

Post by Tamas » Fri Dec 04, 2009 3:50 am

Hezu wrote:I noticed one shop is selling Hitachi Deskstar 7K2000 2 TB for quite reasonable price (~30 € less than the WD GP or Seagate LP in 2 TB size). I tried searching for more information on the Internet but found quite little information. So, has anyone yet any experience with these hard drives?
Here in Hungary it's also a very good priced drive. It costs around 210-220$.

It has 4 or 5? platters, first impressions are:
-very low vibration (this parameter can change from drive to drive, so it's not guaranteed)
-access times around: 11,5-12ms
-loud and very fast seeks, but this can be easily manageable with AAM (Automatic Acoustic Management). This means quiet seeks at the expense of access time degradation.
-max. transfer speed around 135 MB/sec
-average transfer speed around 107 MB/sec

whiic
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Location: Finland

Post by whiic » Sat Dec 05, 2009 11:42 pm

It's 5-platter quite likely. It does have fast sequential transfer rates like 500GB/pl drives but this drive has very low access times as well, which would imply that it uses linear densities typical for 500GB/pl but with lower track densities, since it reduces seek settling time (speeds up seeks). Sounds like something Hitachi might do.

Settling time is more noticeable for random writes than random reads as writing requires higher degree of stability as offtrack write would be disastrous (where as offtrack read only causes HDD to notice that it didn't manage to get data read right and re-read it at next revolution of platter). Some drives have had read 12ms and write 13ms, but the drives that have settling issues due to too high track densities typically have 12ms and 18ms or so. May also cause read access to drop to 13-14 range without allowing seeks to be any quieter (as time is spent settling, not seeking).

Anyway, with lack of random write test benchmarks, this is just speculation. And even with random write tests, it cannot give conclusive evidence whether they use 400 or 500GB platters.

ertr
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Post by ertr » Sun Dec 06, 2009 4:48 am

Why speculate when Hitachi has quite good documentation on their drives available for download?
The 7K2000 is indeed a 5-platter drive.
As for the seek time the typical values are documented as 8.2 ms for reads and 9.2 ms for writes (including settling.)
(Add 4.17 ms for average rotational latency to get the access times.)


[quote="whiic"]It's 5-platter quite likely. It does have fast sequential transfer rates like 500GB/pl drives but this drive has very low access times as well, which would imply that it uses linear densities typical for 500GB/pl but with lower track densities, since it reduces seek settling time (speeds up seeks). Sounds like something Hitachi might do.

Settling time is more noticeable for random writes than random reads as writing requires higher degree of stability as offtrack write would be disastrous (where as offtrack read only causes HDD to notice that it didn't manage to get data read right and re-read it at next revolution of platter). Some drives have had read 12ms and write 13ms, but the drives that have settling issues due to too high track densities typically have 12ms and 18ms or so. May also cause read access to drop to 13-14 range without allowing seeks to be any quieter (as time is spent settling, not seeking).

Anyway, with lack of random write test benchmarks, this is just speculation. And even with random write tests, it cannot give conclusive evidence whether they use 400 or 500GB platters.[/quote]

whiic
Posts: 575
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Location: Finland

Post by whiic » Sun Dec 06, 2009 10:06 am

"Why speculate when Hitachi has quite good documentation on their drives available for download?
The 7K2000 is indeed a 5-platter drive."


Is that stated in some document? It used to be but for some time, number of platters and heads haven't been publicized. From power consumption and noise specs, it has been pretty easy to guess as Hitachi has bothered to mention these values for each variant separately (unlike some other manufacturer which might state some generic value to represent a whole generation of drive family) and this has made determining the number of platters used in downscales easier. However, 7K2000 is only 2000GB with no downscales. There is 7K1000 (4 or 5 pl, 200GB/pl) (1 to 3 platter variants were T7K500 166GB/pl), 7K1000.B (1 to 3 pl, 333GB/pl), and 7K1000.C (1 or 2 pl, 500GB/pl) for reference, though, but even using them for comparison is still speculation and "reason to believe" at best.

"As for the seek time the typical values are documented as 8.2 ms for reads and 9.2 ms for writes (including settling.)"

What is specified and what is real can be two different things (though with Hitachi, they've usually been pretty accurate with their specs, unlike competition (especially Seagate and WD)). If we assumed specs to be accurate, the write access to read access difference being only 1.0 ms would imply "low" track density (i.e 5-platter construction) but it's far from definite proof. Neither are Hitachi's past flagship models a definitive proof. I would say it is a strong likelyhood, though.

whiic
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Post by whiic » Sun Dec 06, 2009 10:23 am

Holy FFFF.... I have to take that back. I was looking for "OEM specs" for 7K2000 but apparently they call the full specs documentation by name "7K2000_A7K2000_Spec_r1.0.pdf" now. No wonder I missed it since usually they make the full specs available to all public no sooner than half a year after release of a new product if even then. This time it's 260 pages of specs and they seem to lack bookmarks on current PDF.

OEM specs indeed are a source of concrete info. I just didn't expect them to be available for the next 6 months to come but they were already online.

"Physical layout" under "4.1 Default logical drive parameters" and "Drive ready time" table under "4.5 Performance characteristics" both confirm it is 5-platter drive. Too bad it's no longer in datasheet (DS7K2000_DS_final.pdf, 2 pages) for quick reference as we shouldn't take availability of OEM specs as granted (other manufacturers don't even offer them and Hitachi usually takes quite a bit longer time to offer them than they did this time).

Kepakko
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Post by Kepakko » Thu Dec 10, 2009 1:19 pm

These are quite cheap; I might replace my 10 disk WD Green RAID array with 6 of these. The idle/seek consumption would be about same according my calculations. It only consumes about 1 W more on idle (according to spcr and Hitachi) than the 2 TB WD Green and the price difference is whopping $40.

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