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Author Topic: Does anyone understand the differences in the Western Digital drives?  (Read 1854 times)
superboyac
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« on: February 17, 2011, 09:13:56 AM »

I'm having a hard time understanding the fundamental differences between the Western Digital hard drives.  It seems they have gone the way of Intel, making a lot of models and being super unclear what the differences are.  It's the same business model...confuse people enough, and they'll just buy whatever.  Anyway, can someone explain them if you know?
Here's what I know:
Caviar Green; these are the cheaper consumer drives.  They use less power, have slower performance (by how much, I don't know), and have 3-year warranties?

Caviar Black: these are the more enterprise grade drives?  This is what I usually buy, simply because I like the 5 year warranty.  They are supposed to perform better, and the use more power.  boo.  I like them, though.

Caviar Blue?
Velociraptor?  I have one, it's supposed to be fast.  My friend told me they're on the outs because of SSD, and he also said he did some tests and the Velociraptors were no faster than his regular 2 TB drives.

RE4?
RE3?

WD has a comparison chart:
http://www.wdc.com/en/pro...ucts/internal/enterprise/

The problem with the chart is that it tells you the distinguishing features, but it doesn't help you figure out which drive you want.  If there are two drives described as:
"Fast, reliable and enterprise-ready."
"Best-in-class performance, unparalleled reliability."
How the hell am I supposed to make a choice?  Just because you put some words in a chart doesn't mean it helps people at all.  It's such corporate bullshit.  Oh, so one is reliable...and the other one has unparalleled reliability.  Super clear, thanks.
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Stoic Joker
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« Reply #1 on: February 17, 2011, 11:42:45 AM »

I'd have to say my favorite (from your chart there) is the: High-capacity and reliability.

Okay so I can either get a High-capacity 2TB drive (well yeah its 2TB), or a Low-capacity 2TB drive? ...Just how the Fluffy Rabbit does that work?!?
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superboyac
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« Reply #2 on: February 17, 2011, 11:45:18 AM »

I'd have to say my favorite (from your chart there) is the: High-capacity and reliability.

Okay so I can either get a High-capacity 2TB drive (well yeah its 2TB), or a Low-capacity 2TB drive? ...Just how the Fluffy Rabbit does that work?!?
What...you don't get it?  what's wrong with you.  Of course you want the high capacity 2TB drive.  duh.  I wouldn't be caught dead with a low capacity 2TB drive.
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JavaJones
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« Reply #3 on: February 17, 2011, 02:55:38 PM »

Undoubtedly WD's drive line-up is confusing, and needlessly so IMHO. While I understand the differences between Green, Black, and Raptor, there are other differences still to consider (e.g. the A/V drives). I'll try to break down what I do know and understand.

First off there are 5 major categories: Desktop, Mobile, Enterprise, A/V, and Solid State. Now I find those categories to be a bit stupid as obviously enterprises may need Solid State or A/V-oriented storage for example. I would just have the 3 as it seems sensible to break it down by market segment. But hey, this is what they have. Ignoring the mobile and solid state areas for now as they don't seem relevant to the discussion, we have 3 categories of traditional hard drive storage lines.

Desktop: Basic home-user stuff, covering the range from low-end (budget) to average user to high-end home user (including gamers). This is where the Blue is, along with Green and Black.

Blue is sort of a legacy line of bog-standard drives with no high performance or power savings tech in particular. They're also the only drives to come with traditional PATA connectors anymore, since they're essentially legacy tech, and they also only go up to 1TB. These will probably go away eventually. Here's The Inquirer's take on them "Blue represents the same old line, mainstream drives with nothing to really stand out from the crowd. This is the drive that goes into OEM PCs, or when your family member wants more storage space in their 'CPU' to hold more pictures from 'the intarnets'. Think value." What's interesting is that these are all 7200RPM drives, unlike the Green Drives, however with lower densities per-platter they may be lower performing anyway. 3 year warranties for these.

Green are squarely focused on power (and heat and noise) savings. They have various power saving technologies, but one of the main ways they save power is using lower rotational speeds. This does reduce performance. This is somewhat mitigated by the large(r) sizes of these drives. In fact the Green series are the largest drives they make (the only ones currently with 3TB capacity). They tend to have large caches as well, presumably to offset the performance issues of lower (or variable) rotational speed. 3 year warranties here as well.

Black are the high-performance, full 7200RPM rotational speed drives. Main differences as far as I can tell - besides the rotational speed - are large cache sizes, up to 2TB size (Blue 7200RPM drives only up to 1TB), and, perhaps most uniquely, 5 year warranties. They also claim they have "dual processing" technology, whatever that might mean. Presumably higher performance. It's also likely that they have a higher Mean Time Between Failures (MTBF) rating (which would justify the 5yr warranty), so in other words they're better manufactured and more rigorously tested to tolerances.

Enterprise: Higher-end storage needs, particularly focusing on reliability and performance. This is where the Raptor and RE series drives come in, as well as some 2.5" form factor options. Unfortunately it's also where the naming gets much less clear as - due to it not being end-user oriented - they have done away with the clean, larger brand differentiations (e.g. Blue, Green, Black), and instead have one clear brand (Velociraptor) for just one of their *6* lines; the rest have obscure code names. Most notably all these drives come with 5yr warranties suggesting higher MTBF and manufacturing standards, testing, etc.

The Velociraptor's are easiest to explain. They're maximum performance and consequently smaller storage size. They differentiate from the Black drives in the consumer area by having even higher rotational speeds at 10,000RPM. These are also one of the drive lines in Enterprise that have some models in the 2.5" form factor.

The WD S25 are 2.5" form factor drives running at 10,000RPM for smaller size computing in the enterprise where performance still matters, though it's not clear to me what the difference between these and the 2.5" raptors would be. Not really worth elaborating much more than that in any case.

Here's where it gets "fun". The RE SAS drives seem to possibly contain additional error correction and vibration compensation tech, but it's not clear if those technologies *aren't* in the other enterprise or even desktop drives. They're certainly the focus of the RE SAS drive marketing though. Other than that, the RE SAS is a 7200RPM drive so differentiating from the RE-4GP below, it's going to be faster overall. Doesn't mention dual processors though, which is interesting.

The RE4 series seems to be the sort of "standard high-end" drive with no particular differentiators, just carrying the Enterprise flagship features of 7200RPM speeds and 5yr warranty with higher MTBF, etc. So no dual processors, no green tech, no vibration compensation or extra error correction.

Finally, the RE3 claims to have extra special vibration compensation tech for "high vibration environments". How this is different from the vibration compensation in the RE SAS drives is not clear. It also only goes up to 1TB capacity, which is interesting. 7200RPM drives.

Finally the RE4-GP is basically the RE series but with green tech. Kind of like a desktop Green Drive with dual processors and a 5 year warranty. So faster than the desktop version and more reliable, but still with power-saving tech and not using 7200RPM max performance speeds.

A/V: There are 3 A/V options. To my mind only 1 is worth talking about because the other two only come in sizes up to 500GB. One of them is evidently a legacy drive as it comes in a PATA option, the other is 2.5" form factor. The WD AV-GP is their high capacity media-oriented (a/v = Audio/Video) drive. It's very similar to a desktop Green Drive, using Intellipower, no dual processors, and only has a 3yr warranty despite claims of "enhanced reliability". The main difference seems to be claims of enhanced noise reduction, down to sub-audible levels. Presumably this is all the same tech as other drives, maybe just particularly tuned for low noise environments, or perhaps binned like CPUs based on inherent post-manufacturing noise characteristics.

So yes, you're right that things are confusing, and needlessly so, but that's *mostly* true in the Enterprise area of their market. That is probably not coincidentally also the area where there are more dollars to spend and there is less concern for purchase paralysis from too many choices, and more likelihood of organizations being really picky about their options and maybe even taking advantage of all the different options.

Now all that out of the way, the reality is there's not much need for the average person (or even a techie) to look at the enterprise drives unless you're planning to put together a RAID solution. *If* you're doing that, then it might be worthwhile A: for the reliability and B: because apparently there are some response time differentiators that make them more suitable for working with RAID controllers that expect a fast response. I haven't been able to get real clarity on that latter issue, but there are claims that e.g. Green Drives are not good in RAIDs (though I think my company has at least 1 RAID 5 array running on 2TB green drives doing just fine for the last year or so). I believe the Caviar Black drives are fine in RAIDs anyways, regardless, and it probably has more to do with issues of the Intellipower variable rotational speed system than anything else.

In the end the way I look at it is this: MTBF is a measure of potential reliability as promised by the manufacturer. If the manufacturer believes their own numbers, they will back it up with a warranty. So if I want reliable, I go for the drive with the longest warranty. In this case only the Caviar Black in the consumer space offers a 5yr warranty. It also happens to be the highest performing, and be more expensive than the Blue or Green series. If you want max capacity, the Desktop Green Drive line is the obvious choice as it's the only one with 3TB at present. If you want to construct a RAID, look at Caviar Black or maybe one of the enterprise drives, although on Newegg a lot of the enterprise drives have surprisingly bad reviews and high failure rates. The Caviar Black seems actually more reliably (by ratings/reviews) than the enterprise drives *and* is less expensive per/GB, so that seems to be the best bet for high-end home use.

Hope that helps.

- Oshyan
« Last Edit: February 17, 2011, 03:08:26 PM by JavaJones » Logged

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superboyac
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« Reply #4 on: February 17, 2011, 03:10:42 PM »

Hope that helps.
You kidding?!  That was amazing, man.  yes it helps very much.  So much, I'm almost compelled to have an article on my website for others to access.

Quote
This is the drive that goes into OEM PCs, or when your family member wants more storage space in their 'CPU' to hold more pictures from 'the intarnets'. Think value."
Oh man, that had me rolling.  Great line man!  You deserve a level 3:


I'm not sure yet, but I think when I build my server I may incorporate RAID into it.  I know it's going to have 10-20 drives, multiple redundancy included.  I just don't know if RAID offers me anything I want or need yet.  I've talked to a LOT of people about this and every single time I am told extremely contradictory things.  One day, i need to have a phone call or face to face talk with someone who really understands this.  I'm not going to write about it anymore.

Anyway, it seems like unless things change I'll stick to my exclusive Caviar Black rule.  Never had a problem yet with those.
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JavaJones
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« Reply #5 on: February 17, 2011, 03:17:33 PM »

Hehe, glad to help. That line is from the Inquirer actually, but definitely funny. cheesy

As we've discussed before, I recommend against RAID for most people. The one exception to that is for high performance applications as even RAID5 can offer performance improvements over a single drive. Doing RAID is a "cheap" way to get high performance *and* high capacity. If all you need is a super fast drive of 100GB or less, go SSD though.

RAID for redundancy is really not that helpful for the home user. The only real reason to use it is for "high uptime" situations, which the home environment is seldom to be considered as IMO. In other words does it really matter in your home server if you have to take the machine down for a few hours to replace a drive and restore the data on it? In a business server environment yes it might matter, so you want the "hot swap" capability and the ability to keep running with data availability even after a drive fails. But for home users RAID is really just an added complexity and failure point IMO. Not to mention it's rather costly to do right. For an 8 drive array you're looking at $500+ just for a good controller, not to mention highly recommended battery backup (UPS for the whole machine will work and is the best option IMO), plus optional caching, etc. It's just not worth the complexity and cost IMO.

If big storage is your concern, go with single drives and avoid RAID headache.

- Oshyan
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f0dder
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« Reply #6 on: February 17, 2011, 05:00:10 PM »

Velociraptor?  I have one, it's supposed to be fast.  My friend told me they're on the outs because of SSD, and he also said he did some tests and the Velociraptors were no faster than his regular 2 TB drives.
Raptors are fast - but a bit too expensive for what you get.

I've got a pair of 75gig raptors, and those were very fast when they initially hit the market... but larger "standard" drives of today are a lot faster, at least with regards to sequential transfer speeds, because of the higher data density of those drives. It's the same story for the velociraptors.

Raptors are supposed to have better access times than the more "traditional" harddrives, though, especially for the 2.5" drives... but they're still molass-slow compared to SSDs. I wonder if the series will live on, if there's a point in being the middle point between ultra-speed SSDs with low capacity, and "slow" mechanical disks with large capacity - especially given the Raptors' high pricetag.

JavaJones: do you have any sensible information on the "dual cpu" thing that some WD drives have? I've seen it mentioned a few places, but haven't found anything on it, except it being used as fluffy marketing snake-oil.
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- carpe noctem
4wd
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« Reply #7 on: February 17, 2011, 05:53:05 PM »

Possibly a couple of other things to mention, (or maybe not if no-one's bothered smiley ), that differentiates Consumer from Enterprise:

Enterprise drives usually have higher IOPSw, (as you would hope if they're in a server environment), and a shorter error recovery time, (TLER).

Here's a WD document, (PDF), to explain the last bit: TLER

JavaJones: do you have any sensible information on the "dual cpu" thing that some WD drives have? I've seen it mentioned a few places, but haven't found anything on it, except it being used as fluffy marketing snake-oil.

This might help: Dual-Processor Hard Drives – All Good Or All Hype?
« Last Edit: February 17, 2011, 05:59:50 PM by 4wd » Logged

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JavaJones
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« Reply #8 on: February 18, 2011, 03:00:53 PM »

Good extra info there 4wd. I don't see IOPS figures quoted on WDs site though, and I'm wondering just how big the difference can be. Judging by the Wikipedia article, SSDs can blow HDs away in IOPS anyway. The TLER issue is probably more the reason for the RAID-specific drives. I do wonder how important that really is as well because, as I said, I have 4 green drives operating in a RAID off a fairly decent RAID card for the last year with no problems (in a business environment). But reading more about all this now, I'm seeing that may not be considered a "proper" configuration. We're about to buy a new mirror server and I'm looking at what drives to buy; originally considering the AV-GPs, but after seeing Newegg's reviews on some of the enterprise stuff I'm concerned...

- Oshyan
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4wd
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« Reply #9 on: February 18, 2011, 06:08:40 PM »

This Wikipedia articlew seems to indicate that you can switch the feature on/off in HDD firmware on even Consumer class drives because of the prevalence of chipset based RAID these days.

The article mentions a WD program to do it, WDTLER.EXE, and there's also WDIDLE.EXE if you want to change the Intellipark time.

I do wonder how important that really is as well because, as I said, I have 4 green drives operating in a RAID off a fairly decent RAID card for the last year with no problems (in a business environment).

It could be that the drives in the array have yet to experience an error severe enough that the RAID controllers error recovery is triggered.  Being a year old I would hope they're still reasonably reliable.

After having a search around various forums, it appears that WD, (don't know about Seagate ECR, Samsung CCTL, etc), have disabled the ability to toggle TLER in Consumer class drives from late 2009 - whether it's across the board, range or model specific I'm not sure.

Also that good RAID controllers seem to be able to handle Consumer class HDDs much better than cheaper RAID cards, I would also think any onboard based RAID controller is probably more tolerant of Consumer class drives.
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