Western Digital Caviar Green 2TB Hard Drive Review

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Western Digital Caviar Green 2TB Hard Drive Review

Manufacturer’s Product Page: WD Caviar Green 2 TB
Model Number: WD20EADS
TechWiki Info: Western Digital Caviar Green 2TB SATA - TechWiki
Price: Click Here to Compare Prices
Warranty: 3 years




In a computing world that is seeing its storage needs rapidly expand with the introduction of HD movies and other large file formats, we have seen a quick surge in the capacities of today’s hard drives. While we all know that the recent SSD revolution has produced some of the fastest consumer-available storage mediums around, these drives lack the capacity to store large amounts of data at a reasonable price. This is where drives like the Western Digital Caviar Green 2TB come into the equation. They offer vast storage capacities while retailing for a fraction of what higher-end SSDs go for while offering more than acceptable performance.

In the past we have looked at many of the various storage options available but this is the first drive we are going to put under the microscope which is not marketed or designed for enthusiasts or speed-seekers. While Western Digital’s own Black and VelociRaptor series steal the lime light, these Green series drives go about their business giving not only great bang for your buck performance but abilities that you cant get in other lines. After all, a VelociRaptor may make a great OS drive, but sticking it in an external enclosure is not such a great idea due to the heat it produces but it is these situations the Green series is designed for. Based on previous experiences, an extremely fast hard drive for the OS (or Solid State drive) combined with a Green for storage purposes is about as good a one-two combination as you can get.

These drives are all about efficiency, whether that be in reduced power consumption or noise. However, to get this reduced power consumption and noise Western Digital had to design this drive to rotate much slower and WD states each one may perform differently as they are set to their optimum speed at the factory. As such, speed can vary from 5400 to 7200RPMs and based on previous use, we are more inclined to believe they are usually on the lower end of that spectrum. In other words these drives are designed to be data drives first and foremost and not ultra low latency, “high performance” products. When you consider the fact that a millisecond or ten really doesn’t matter in a drive which has data storage as its primary purpose, this seems like a brilliant move to us. Catering to different niches with separate products lines (Green, Blue and Black in WD’s case) just makes sense to us.

As a nice little bonus, the Green series are priced to be a much greater value when compared to the Black, Blue and VelociRaptor series. In the case of the WD 2TB iteration, we have recently seen them on sale for as little as $159, but a more typical price is $170 which translates into a lot of storage space for your hard earned dollar. This frugality combined with its efficiency is the main reason why we are so interested in seeing what this drive is made of. We will of course be putting it through the wringer to see how much performance the Western Digital Green 2TB has to offer but our main focus is going to be on how well it does as a storage drive. One way or another, we are excited by the possibilities this drive opens up for consumers.

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Specifications

Specifications

<img src="http://images.hardwarecanucks.com/image/akg/Storage/WD2TBGreen/specs.jpg" border="0" alt="" />

<img src="http://images.hardwarecanucks.com/image/akg/Storage/WD2TBGreen/specs1.jpg" border="0" alt="" />

<img src="http://images.hardwarecanucks.com/image/akg/Storage/WD2TBGreen/specs2.jpg" border="0" alt="" />

<img src="http://images.hardwarecanucks.com/image/akg/Storage/WD2TBGreen/specs3.jpg" border="0" alt="" />
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A Few Features Under the Microscope

A Few Features Under the Microscope

It is a shame that this Green Model doesn’t come with dual stage actuators as this would certainly help it in the latency department (the one area these drives really, really lag behind modern 7200rpm drives) as you will see later. Hopefully, at some point in the future this cutting edge technology will trickle down to the Green line but in the mean time there are many other technologies hidden inside this pretty faced drive. As we mentioned in the introduction, Western Digital didn’t stop at making it a 5400’ish rpm drive and call the power savings “good enough”. Rather, they did add in some other impressive tweaks to further reduce power consumption. Let’s take a moment and go over these improvements and other technologies the Caviar Green 2TB has.


NoTouch

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As with all Western Digital drives this drive features “NoTouch” technology. This is a fancy way of saying your drive heads never touch the platters and during shutdown automatically park themselves. Except for a few of us old timers can anyone really remember having to manually tell their hard drive to park the heads? It was a big deal back in the day…but now every drive does this. As for never touching the heads, it's same deal; if your heads do hit the platter its called “cow belling” and your HDD dies while making a very distinctive cow bell-like sound.


IntelliSeek

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Another feature which is basically par for the course now is IntelliSeek. What this features is and does is fairly simple to explain and yet it is still a very elegant solution to an age-old problem. On older drives the seek head would zip across the platter as soon as it could and then wait for the sector it needed on the platter to rotate around so it could read it, and then zip to the next one and wait. Rinse and repeat and you basically have an idea of how things used to work. What IntelliSeek does is calculate the best time to move the heads so that as soon as it reaches its destination, the sector is in position to be read. This keeps the arm in motion so that its electrical motor doesn’t have to overcome initial startup resistance which requires on average three times the amount of power (and certainly creates more noise). Western Digital states this reduces vibrations and power consumption and we believe them as it is simply a better way of doing things.


StableTrac

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Next up is StableTrac, which is nice to see in a more value orientated product line like the Green. StableTrac means this HDD has it’s drive shaft anchored at both ends, and not just on one end like was the norm not too long ago. In this case this feature is used for reducing vibration and noise while increasing life expectancy. It really is nice to see this improvement trickle down to Western Digital's other drives as does make for both a more durable and silent running drive.


IntelliPark

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The last feature we are going to look as is a double edged sword called IntelliPark. For the most part we have no issues with the assortment of power saving features Western Digital has built into their Green Line; however this feature is one we really wished Western Digital had included a way to over-ride (preferably via a jumper pin like they have for Spread Spectrum Clocking and PUIS; two other less than perfect "one size fits all" options). What this feature does is give the Green line the ability to park its head after a certain period of inactivity (usually about 8 seconds). On the surface this is a great idea as it will further reduce power consumption by reducing resistance drag on the spindle motor but many setups and operating systems do NOT like this and it can cause issues. One of the best examples of this is MS Home Server and Linux, both of which throw errors and fits when Greens are used.

 

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A Closer Look at the Western Digital Caviar Green 2TB

A Closer Look at the Western Digital Caviar Green 2TB

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When we first looked at this drive the biggest thing which stood out is the fact it looks almost identical to the Western Digital 2TB Black we reviewed awhile back. Please don’t get us wrong, there is more than enough to distinguish the two from each other and unless you are literally colour blind and can’t read the Queen's English you will have a tough time mixing these two drives up. In a nutshell, you have the same black and silver coloured metal enclosure with black accents as the “Black” line but instead of a black striped label you have a green one.

We understand why Western Digital went with the same metal chassis for both their high-end drives as this does simplify the logistics of both lines which does help keep the manufacturing costs down. When all is said and done, the Green series is a more value orientated product and anything which can help keep the price down has to be considered a good thing.

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As with the Black line, this product is a down right beefy product that has a good amount of heft to it. This weight is of course due to the fact that just like the Caviar Black 2TB, Western Digital has to use FOUR 500GB platters in this drive. Also in keeping with the previous 2TB we looked at, this drive is “only”2,000,000,000,000 bytes and not 2TiB (i.e. 2,199,023,255,552 bytes) so your OS will only show it as an approximately “1.81TB” drive.

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According to the label, this power miser of a drive is rated to draw a maximum of 0.45 amps off the 12 volt line (5.4 watts) and 0.60 amps off the 5 volt line (3 watts), for a combined total of 8.4 watts. This is over a full watt LESS (1.05 watts to be precise) than the Caviar Black 2TB model we reviewed which sucked a combined total of 9.45 watts of power. This may not sound like much but considering the Black 2TB was already considered quite efficient, it is impressive to say the least.

On the surface a singe watt of savings doesn’t sound like much (though this IS 12.5% less power consumption over the high end product), but this does add up when you have a bunch of these drives running. In addition, the noise envelope of the Green series is substantially lower than the Blacks which could be a godsend if you have several HDDs in the same enclosure.

 

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Under The Hood

Under The Hood

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Like many newer drives, this hard drive does not use attached cables to move data and power from the PCB to and from the drive itself. Rather, it relies on the perfect placement of the spindle power connections (the hard points near the orange cable in the above picture) and a multi prong data port similar to what is seen in laptops to connect the SATA drive to the motherboard. To ensure proper alignment there are two small plastic alignment posts which have accompanying holes in the PCB.

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In the continuing trend of Western Digital frugally reusing as much as possible from one line to another, the PCB which graces the Caviar Green 2TB is a dead ringer for the one found in the Caviar Black 2TB. As we have said before, this is not a bad thing and anything which can help keep prices down has to be considered a good thing. Of course, while the PCB is the same, the components on it are not necessarily going to be.

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The cache this drive sports has been boosted from the previous generations 16MB to 32MB and while we are not a proponent of “more is always better” we can understand why Western Digital did this. The reason we are not overly impressed is the difference in performance between 2MB and 8MB was minor, and the improvement from 8 to 16 was even smaller, which means the 16MB to 32MB increase is smaller still.

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The external cache module this drive sports is made by Winbond and not Hynix like the Black 2TB has. Normally we would be curious why Western Digital didn’t go with just one supplier for all their lines but the answer is pretty obvious: price.

It is actually interesting that WD decided to go with an external cache module on this drive in the first place. After all, the Black line got along very nicely without one (instead relying on integrated cache on the Marvel SoC) until they went with more than Marvel could offer on their SoC’s: 64MB of cache. In either case and to be more precise, the single Winbond chip is model W9425G6EH-5. This is a 2.5 volt, 256megabit (32MB) DDR SDRAM, TSOP II 66pin chip. Since this is the “-5” version of this model, it means this particular one is rated for a maximum speed of 200mhz @ CL3.

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Since this PCB sports an external cache chip, we knew for a fact that it wasn’t going to use the same controller as the Black line. For the time being, a dual processor controller chip still remains the realm of the Black line and only the Black line (though we have a sneaking suspicion the next generation of the Raptor line will probably have one too). Like we said, a single core controller is what we were expecting and that is what we got; however, what we were not expecting was to see the Marvel 88i8945 make another appearance.

We can honestly say we got our hopes up when we saw this chip as it is the same model the 2TB Black uses. Unfortunately, they are not the exact same chip. The Caviar Black 2TB uses the Marvel 88i8945P, whereas the Caviar Green uses the non P version (i.e. just a Marvel 88i8945). As we have said in previous reviews, Marvel is less than forthcoming with information when it comes to their System on a Chip (SoC) controllers. What is known is the P in the Black line obviously stands for Performance (much like the “E” in the previous generations 88i8845 stood for enhanced).

We wouldn’t be overly surprised if this chip also comes with what Marvel calls Tightly Coupled Memory (i.e. onboard memory) but obviously Western Digital felt more comfortable relying on an external solution rather than using it.

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Also as expected, the motor controller on the 2TB Caviar Green is made by ST Microelectronics, which is the same manufacturer of all the Western Digital drives we have looked at. To be precise this is a SMOOTH L7251 3.1 controller chip which is not the same as the 2TB Caviar Black’s 3.2 revision of the L7251. However, a slightly earlier revision or not, it is still a damn good controller. The easiest way to understand what this chip does is to look at it this way: if the Marvell chip is the “brain” of this setup then this chip is the Central Nervous System. In a nutshell, this controller is responsible for governing darn near everything related to mechanical and electronic power functions of the Green 2TB.

 

[AkG]

Testing Methodology

Testing Methodology

Testing a hard drive is not as simple as putting together a bunch of files, dragging them onto folder on the drive in Windows and using a stopwatch to time how long the transfer takes. Rather, there are factors such as read / write speed and data burst speed to take into account. There is also the SATA controller on your motherboard and how well it works with SSDs to think about as well. For best results you really need a dedicated hardware RAID controller w/ dedicated RAM for SSDs to shine. Unfortunately, most people do not have the time, inclination or monetary funds to do this. For this reason our testbed will be a more standard motherboard with no mods or high end gear added to it. This is to help replicate what you the end user’s experience will be like.

Even when the hardware issues are taken care of the software itself will have a negative or positive impact on the results. As with the hardware end of things, to obtain the absolute best results you do need to tweak your OS setup; however, just like with the hardware solution most people are not going to do this. For this reason our standard OS setup is used. However, except for the XP load test times we have done our best to eliminate this issue by having the drive tested as a secondary drive. With the main drive being a WD 320 single platter drive.

For these tests we used a combination of the ATTO Disk Benchmark, HDTach, HDTune, Cystal Disk Benchmark, h2benchw, SIS Sandra Removable Storage benchmark, and IOMeter for synthetic benchmarks.

For real world benchmarks we timed how long XP startup took, Adobe CS3 (w/ enormous amounts of custom brushes installed) took, how long a single 4GB rar file took to copy to and then from the hard drives, then copy to itself. We also used 1gb of small files (from 1kb to 20MB) with a total 2108 files in 49 subfolders.

For the temperature testing, readings are taken directly from the hottest part of the drive case using a Digital Infrared Thermometer. The infrared thermometer used has a 9 to 1 ratio, meaning that at 9cm it takes it reading from a 1 square cm. To obtain the numbers used in this review the thermometer was held approximately 3cm away from the heatsink and only the hottest number obtained was used.


Please note to reduce variables the same Windows XP OS image was used for all the hard drives.

For all testing a Gigabyte GA-P35-DS4 motherboard was used. The ICH9 controller on said motherboard was used.

All tests were run 4 times and average results are represented.

Processor: Intel Core 2 Quad Q6600 @ 2.4 GHZ
Motherboard: Gigabyte GA-P35-DS4
Memory: 4GB G.Skill PC2-6400
Graphics card: Asus 8800GT TOP
Hard Drive: 1x WD 320
Power Supply: Seasonic S12 600W

SSD FIRMWARE (unless otherwise noted):
G. Skill Titan: 0955
G.Skill Falcon: 1571 (AKA FW 1.3)
OCZ Apex: 955
OCZ Vertex: 1.3 (AKA FW 1571)
Patriot Torqx: 1571 (AKA FW 1.3)
Corsair P64: 18C1Q
OCZ Summit: 1801Q
A-Data S592: 1279 (AKA PRE 1.1 FW)
OCZ Agility EX 60GB: 1.3 (AKA 1.4 for MLC Indilinx Drives)
Kingston SSDNow V 40GB: 02G9
G.Skill Falcon 2: 1881 (AKA 1.4)

 

[AkG]

Read Bandwidth / Write Performance

Read Bandwidth

For this benchmark, HDTach was used. It shows the potential read speed which you are likely to experience with these hard drives. The long test was run to give a slightly more accurate picture.

We don’t put much stock in Burst speed readings and this goes double for SSD based drives. The main reason we include it is to show what under perfect conditions a given drive is capable of; but the more important number is the Average Speed number. This number will tell you what to expect from a given drive in normal, day to day operations. The higher the average the faster your entire system will seem.

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With just an average of 87.2MB/s the Green 2TB is one of the slowest drives we have tested. However, this is only half the story as the Caviar Green is also the only 5400rpm...ish drive we have looked at. The fact that there is under 10MB/s difference between the Green and the 1TB Black is actually impressive when you think about it. Remember, the Green drive line are designed for low noise and power efficiency first and performance second and that it can come this close to a Caviar Black IS impressive in our books.

The reason this drive does great in this test is because it has down right amazing platter densities and we firmly believe its low spindle speed and single core controller are the limiting factors. Of course, if it was a dual core, 7200rpm drive it wouldn’t be as efficient and its entire "raison d’etre" would be extinguished.

Write Performance

For this benchmark HD Tune Pro was used. To run the write benchmark on a drive, you must first remove all partitions from that drive and then and only then will it allow you to run this test. Unlike some other benchmarking utilities the HD Tune Pro writes across the full area of the drive, thus it easily shows any weakness a drive may have.

<img src="http://images.hardwarecanucks.com/image/akg/Storage/WD2TBGreen/write.jpg" border="0" alt="" />
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Once again on the surface of things the write speeds of this drive may not seem all that impressive; but looks can be deceiving. As we said earlier: this chart is full of past and current high performance products and only high performance hard drives. If you look closely you can see that the Western Digital Caviar Green 2TB is almost as fast as the last generation (1TB version) Black. Let me say that again: a GREEN drive is almost as fast in write speeds as a BLACK. Impressive.

 

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Crystal DiskMark / Random Access Time

Crystal DiskMark

Crystal DiskMark is designed to quickly test the performance of your hard drives. Currently, the program allows to measure sequential and random read/write speeds; and allows you to set the number of tests iterations to run. We left the number of tests at 5. When all 5 tests for a given section were run Crystal DiskMark then averages out all 5 numbers to give a result for that section.

Read

<img src="http://images.hardwarecanucks.com/image/akg/Storage/WD2TBGreen/cdm_r.jpg" border="0" alt="" />
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If we were impressed with the HD Tach read results, we are almost astounded by the Crystal DiskMark read numbers. Yes, in the all critical small 4k reads this drive is over 32% slower than a 1TB Black (its nearest competitor), but the Green is built not as an OS drive (where small 4k read and writes matter the most) but as a data drive where medium size and sequential performance count the most. It is here that the Caviar Green is only about 5MB/s and 1.4MB/s slower than a Caviar Black. This works out to be a moderate difference of 8.6% for the 512KB test and a mere 1.2% for sequential read speed. Dang, this drive is FAST for a Caviar Green.

Write

<img src="http://images.hardwarecanucks.com/image/akg/Storage/WD2TBGreen/cdm_w.jpg" border="0" alt="" />
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As expected, the performance numbers this drive posts in the CDM write tests are not as glowing as they were with the read speeds. We do have to wonder how much better this drive would have been if Western Digital had included a dual actuator and dual processor. I am sure that the difference in power consumption would have been minor and I for one would be willing to put up with a moderate increase in electricity if it meant more performance with the same kick ass low noise envelope the Greens are famous for.

Random Access Time

To obtain the absolute, most accurate Random access time, h2benchw was used for this benchmark. This benchmark tests how quickly different areas of the drive can be accessed. A low number means that the drive space can be accessed quickly while a high number means that more time is taken trying to access different parts of the drive. To run this program, one must use a DOS prompt and tell it what sections of the test to run. While one could use “h2benchw 1 -english -s -tt "harddisk test" -w test” for example and just run the seek tests, we took the more complete approach and ran the full gamut of tests and then extracted the necessary information from the text file. This is the command line argument we used “h2benchw 1 -a -! -tt "harddisk drivetest" -w drivetest”. This tells the program to write all results in english, save them in drivetest.txt file, do write and read tests and do it all on drive 1 (or the second drive found, with 0 being the OS drive).

<img src="http://images.hardwarecanucks.com/image/akg/Storage/WD2TBGreen/random.jpg" border="0" alt="" />
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There is no getting around the fact that the random access speed this drive has (and we use the word “speed” more than a little bit ironically here) is poor. This makes perfect sense to us and as anyone who has lowered the AAM of their 7200rpm drive to quiet it down knows: low latency and low noise do NOT go together. If this is the only major concession Western Digital had to make we will be more than happy with this Caviar Green drive.

 

[AkG]

ATTO Disk Benchmark

ATTO Disk Benchmark

The ATTO disk benchmark tests the drive’s read and write speeds using gradually larger size files. For these tests, the ATTO program was set to run from its smallest to largest value (.5KB to 8192KB) and the total length was set to 256MB. The test program then spits out an extrapolated performance figure in megabytes per second.

Read

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As expected, the ultra dense platters make this a real beast in read speeds. Sure, it may not compare to the new Caviar Black 2TB or VelociRaptor…BUT those drives cost a heck of a lot more too. From about the midpoint of the ATTO tests this GREEN drive is actually faster than a Caviar Black 640GB and only slightly slower than the 1TB Caviar Black (about 3MB/s on average). As we have said before, dense platters can only get you so far and the dual actuator, dual controller 7200RPM Caviar Black 2TB eats this drive for breakfast with about a 40MB/s difference in speed. On the plus side, at the low end of the ATT test suite all the hard drives (and most of the Solid State Drives too) had very similar postings with all of them being in the same “ballpark” so to speak. All in all, we are really coming to be impressed by the read performance of this iteration of the Green series, something which we were not really expecting.

Write

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Once again, we see that the write speeds of this drive were again very close to the 1TB Caviar Black with only a 3 - 4MB/s separation. While this was somewhat expected, what was VERY interesting was that the Caviar Green 2TB’s performance curve is very, very similar to the 640GB version of the Caviar Black.

 

[AkG]

IOMeter / IOMeter Stutter Test

IOMETER

IOMeter is heavily weighted towards the server end of things, and since we here at HWC are more End User centric we will be setting and judging the results of IOMeter a little bit differently than most. To test each drive we ran 5 test runs per HDD (1,4,16,64,128 que depth) each test having 8 parts, each part lasting 10 min w/ an additional 20 second ramp up. The 8 subparts were set to run 100% random, 80% read 20% write; testing 512b, 1k, 2k,4k,8k,16k,32k,64k size chunks of data. When each test is finished IOMeter spits out a report, in that reports each of the 8 subtests are given a score in I/Os per second. We then take these 8 numbers add them together and divide by 8. This gives us an average score for that particular queue depth that is heavily weighted for single user environments.

Please Note: We have removed all Solid State Drive results from this chart as they tend to compress all hard drive results into a flat smear at the bottom of the chart. This is the only test where SSD results will not be shown in a Hard Disk Drive review.

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As with many hard drives on the market today, the Western Digital Caviar Green 2TB prefers deep que depths. However, and unlike the performance models we have seen in the past the Green does peak before the que depth does. This is not due to the fact that it is only a single controller based unit as the Western Digital VelociRaptor is a single controller unit as well. The reason for this is much simpler: this drive has an extremely high random latency and has a relatively slow spindle speed.

All this comes as no surprise as this drive has not been designed (even in the designers dreams…or worst nightmares) as a server grade storage device so the chances of it ever seeing que depths beyond four (and most likely one or two to be honest) are slim. .

IOMeter Stutter Test

In our usual IOMeter test we are trying to replicate real world use where reads severely outnumber writes. However, to get a good handle on how well a given drive will handle a worse case scenario we have also run an additional test. This test is made of 1 section at que depth of 1. In this test we ran 100% random. 100%writes of 4k size chunks of information. In the .csv file we then found the Maximum Write Response Time. This in ms is worst example of how long a given operation took to complete. We consider anything higher than 333ms (one third of a second) to be a good indicator that stuttering may happen, with the higher the number the worse the duration of the stutter will most likely be.

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While we usually don’t include the “Stutter” test for hard drives, as this is mainly a Solid State Drive issue (or was) we think it was worthwhile to see how long it really takes for a totally random string of writes to happen. While the average is higher than the other hard drives tested it still was decent, what was concerning was the maximum numbers this drive posted. In fact, this is probably the best example of how hobbled this single controller, single actuator, high latency drive is as the Caviar Green posted maximum numbers usually reserved for Solid State Drives. With that being said, and to be totally fair and balanced, they are still below the no man’s zone of 333ms where stuttering can happen.