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7200RPM WD Blacks are designed to be faster then WD Blues/Greens.

They are the same speed, same cache, etc., what really makes them actually faster?

Does it have to do with spin up/down speeds or what?

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The official Western Digital flyer about these has some info. At a glance, I'd guess the large amount of cache available on the Blacks has the most significant performance impact (depending on usage patterns; you can't really call a drive "faster" than another without knowing how you are planning to use it). –  Jason C Mar 9 at 21:30

4 Answers 4

The list of differences I managed to compile while shopping for xmas was:

  1. Blacks supposedly have dual processors, which apparently gives higher throughput and lower latency. They also have a 5 year warranty.

  2. Greens aren't 7200 RPM drives. WD lists them as "Intellipower", which they originally claimed meant that they varied their speed dynamically from 5400-7200 RPM to help save power when not under heavy use. These claims were quietly replaced by a very fine print definition of each individual drive is manufactured with a slightly different speed. Independent testing has confirmed that they are ~5900 rpm drives. They also have a reputation for a high failure rate, especially early on and have only a 2 year warranty. They have a "feature" where they park the heads after 8 seconds of inactivity supposedly to save a little more power, but this puts more wear and tear on the drive and people generally recommend disabling it. Bottom line: stay away from these drives.

  3. The Red edition is just a Green with the Time Limited Error Recovery ( TLER ) feature enabled in the firmware, and a little bit more QA before they go out the door, with a 3 year warranty. TLER only matters for use in RAID arrays and really doesn't seem to be very important to other users.

  4. The "RE" Raid Edition are black drives with TLER and a 5 year warranty, and high price. They are aimed at corporate servers that are always on, always accessed.

  5. The Blues are the run of the mill average. I ended up getting 3 of these and put them in a RAID 10 for both speed and reliability, for less than the price of a 10,000 rpm Velociraptor. The array pushes ~500 MB/s.

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Any references for your comments on the Green drives? They are supposedly designed to be quieter (and less power consumption), lower speed is a by-product of that... Also they tend to be more expensive than the Blue. Why do you say they are crappy and to stay away? (I haven't yet seen the failure rate, so I don't know about that...) –  AviD Mar 5 at 21:58
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If you want to discuss something, create a chatroom please. Otherwise I'll have to purge the comments here. Comments should be used only to ask for clarification or point out mistakes in a post. –  slhck Mar 6 at 7:52
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More on topic: Please source your statements about drive reliability. The last thing we need is more unsubstantiated rumour about which drives are more reliable than others. –  bloopletech Mar 6 at 10:52
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This answer is incorrect and contains a lot of FUD, there are actual differences both technical and in the strategy used by the firmware of each type. –  JamesRyan Mar 6 at 10:56
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The Green drives have very aggressive head parking (~8 seconds). This seems to be what causes such a high failure rate when used in certain configurations that read/write constantly (eg/ in a storage RAID). –  Affine Mar 6 at 14:53

Other factors to consider include interface speed, platter density, speed of the cache, and the design of the drive controller.

Blacks also have support for various commands (e.g TLER) that are important for enterprise users (RAID storage, etc) but generally not useful to the home user.

WDC have a list of the features unique to Black on their site.

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I'm pretty sure it is the "Re" or "Enterprise" drives that feature RAID-optimized TLER. –  kmarsh Mar 5 at 16:38
    
Possibly. Certainly not the Green, at least. –  RJFalconer Mar 5 at 16:39
    
TLER is not just important for enterprise, it is the one important feature on a hard disk to avoid losing data. A drive without TLER is broken by design, it means that the first time a sector fails its checksum (which will inevitably happen with age, but may randomly happen due to many other reasons) the sector will be remapped and the data is never again accessible. TLER will cause a user-noticeable delay and generate a relocation event that SMART tools will pick up. It gives you the possibility to ignore the event or to back up data if that has not already happened. –  Damon Mar 6 at 11:36
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"Green" on the other hand, is already self-explaining. The Green Movement is a moronic, misled ideology to "save the environment", which only reduces performance and destroys the environment. Green drives will save a few milliwatts over their lifetime by spinning the disk slower, but due to the way harddisks work (air bearing) this greatly reduces the drive's resilience to vibration and its overall lifetime. Replacing drives more often due to decreased lifetime is an economic benfit for the manfacturer (more sales) but damages environment much more than a few milliwatts extra. –  Damon Mar 6 at 11:40
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@Damon I'm pretty sure you have the TLER bit mixed up a little. Without TLER, most modern drives will attempt to reread the bad sector until successful and then write the data to the remapped sector. This causes the user-noticeable delay you mention, but for non-redundant discs there's not much else you can do if recovering the data is desirable. For RAID setups, which can usually reconstruct the data for the bad sector, TLER is useful because it will stop the attempted rereads after a short period of time and report the read failure for the RAID controller to handle. –  JAB Mar 6 at 18:40

To answer the first part:

7200RPM hard drives and types.
What makes them so different?

Nothing. There is nothing special about 7200 RPM drives.

They are often faster than their lower RPM drives because most mechanical hard drives store their information on a rotating platter. Spin the platter faster and it passes faster between the point where the information is read or written.

If you take a platter from a 7200 RPM drive, slow the drive down to 5400 and re-low level the drive then you will end up with a drive reading and writing at ¾ of the 7200 speed drives.

(5400/7200 = 3/4, or ¾).

It will also have a slower random access time since to access a piece of random data you need to wait an average of half a platter rotation. If the platter moves faster then this takes less time.


Is 7200 RPM special?

No, drives have been produced with all kinds of rotation speeds, platter densities, number of platters etc etc. It is just that lots of the recent drives are either 5400 RPM or 7200 RPM. Those 7200 RPM's often get other beneficial features while the 5400 RPM often get aimed at low power, low noise environments.

That is not to say that those are the only speeds. Drives I have used in the last 6 years included rotation speeds of 4200 RPM (bigfoot), 5400 RPM (original from my laptop), 5900 RPM (my newest 4TB drive) and 15k RPM (a small SAS drive in my desktop).

Higher than 15K RPM does not seem to be used. Probably because the added effort to does not warrant the performance gained.

Lower than 5400 RPM is also rare. Usually only in ultra-low-power drives or in drives with large platters (e.g. the bigfoot series which was the last 5 ¼ consumer drive I saw).

Still, even if it is used a lot it is nothing special.


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One advertised difference is "dual processors".

All HDD designs are a balance of audio qualities, power saving plans, disk head movement optimizations, cost and so on. I've found Black drives to be fairly noisy, so I would guess the optimizations are slanted towards performance over audio qualities.

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