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Western Digital Black vs. RE Hard Drives

Written on September 29, 2014 by Matt Bach


Here at Puget Systems, we sell a lot of hard drives. In fact, in the last year alone we have sold over 2,000 traditional platter-based hard drives, nearly half of which were WD (Western Digital) Black drives. However, since we are constantly looking for ways to improve our product line - and by extension the computers we sell - not even a product that has this huge number of sales is completely safe from scrutiny. In fact, we have recently decided to replace the WD Black drives from many of our systems with the enterprise-level RE drives that are also made by WD.

Western Digital Black and RE

It may appear to be a risky move to replace our all-time biggest selling hard drive line, so in this article we are going to compare the Black and RE lines and show why we believe that this is a good move. One thing we want to note is that we will only be comparing the 2, 3, and 4TB versions of the Black and RE drives and skipping the 1TB versions. At the time this article was written, the RE 1TB drive is an older revision than the Black 1TB drive so it does not conform to the normal differences between the two model lines.

Because there are so many specifications and features to go over, we will be dividing this article into separate sections based on the categories that WD uses in their spec sheets. These categories include basic specifications, features, performance, reliability/data integrity, power management, environmental specifications, and physical dimensions. If you would rather just see a summary of why we are making this move, feel free to jump ahead to the Conclusion section. Likewise, if you would rather just see all the specifications at a glance without any of our commentary, simply expand the option below:

[+] WD Black vs. RE Specification Comparison


Basic Specifications

Basic Specifications Black 2/3/4 TB
(FZEX Series)
RE 2/3/4 TB
(FYYZ Series)
Interface SATA 6Gb/s SATA 6Gb/s
Formatted capacity 2/3/4 TB 2/3/4 TB
Native command queuing Yes Yes
Form factor 3.5-inch 3.5-inch
RoHS compliant Yes Yes
Newegg Price $140/$180/$235 $160/$210/$270

From a very basic standpoint, the two model lines are essentially the same. They are both 3.5-inch SATA 6GB/s drives that include 2, 3, and 4TB versions. The main difference we want to point out here is the price. If you were to purchase these drive from Newegg as parts, the RE drives are between $20 to $35 more expensive than the Black drives which works out to be about a 15% price premium for RE drives.


Features Black 2/3/4 TB
(FZEX Series)
RE 2/3/4 TB
(FYYZ Series)
TLER Support No Yes (7 seconds)
Vibration Protection StableTrac
RAFF Technology
SED Support No "Optional"
Rated TB/year Unlisted
(estimated 55)

The features listed above are the majority of what sets RE drives apart from Black drives. The first feature we want to talk about it support for TLER (Time Limited Error Recovery) which limits the amount of time a hard drive can spend trying to recover from an error. Normally, if a data error is detected the hard drive will attempt to recover the data and repair the error. Depending on the nature and severity of the error, this can take anywhere from a few milliseconds to a couple of minutes. Normally, this isn't a big deal - it just results in the data not being available for a bit longer than normal. However, RAID controllers only allow for a short amount of recovery time (usually about 7-14 seconds) before the controller assumes that the drive is having problems, drops the drive from the array, and marks the array as degraded.

What TLER does is limit the amount of time the hard drive can spend trying to repair an error before giving up. Since many types of RAID have built-in error correcting, it is preferable to let the RAID itself repair the error than to let the hard drive drop and degrade the RAID array. While TLER is absolutely great if the drive is used in a RAID array, it typically will not have any impact on a drive that is simply a stand-alone drive. 

While both Black and RE drives have StableTrac (where the motor shaft is secured at both ends to reduce vibration) and VCT (Vibration Control Technology), RE drives also have additional vibration protection through RAFF technology (Rotary Acceleration Feed Forward). RAFF technology is an advanced form of vibration cancelation that is intended to combat both performance degradation and reduced reliability due to vibration from sources like fans and other hard drives. Through the use of multiple linear accelerometers and microprocessors, a drive with RAFF technology is able to compensate and mitigate the effects of vibration on a hard drive.

If you have multiple hard drives (whether they are in a RAID or not), vibration protection is an extremely beneficial technology. In fact, RAFF technology is the main reason why WD doesn't have a recommend limit for the number of RE drives you can install in a system, but doesn't usually recommend using more than a couple of Black drives.

In addition to TLER and RAFF, RE drives also have "optional" support for SED (Self-Encrypting Drive technology) while the Black drives do not. We put optional in quotes because even though WD lists SED very prominently on the WD RE product page and spec sheet, it turns out that you cannot actually purchase an RE drive in the U.S.A. that has SED support. More information on SED is available in our Introduction to Self-Encrypting Drives article.

Finally, WD RE drives are rated to be able to handle 550 TB/year of data. Black drives do not have an official rating, but the industry standard for desktop drives is about 55 TB/year. So compared to the industry standard, RE drives should be able to handle about 10 times as much data before showing signs of wear.


Performance Black 2/3/4 TB
(FZEX Series)
RE 2/3/4 TB
(FYYZ Series)
Buffer to host 6 Gb/s 6 Gb/s
Transfer Rate to/from drive (sustained) 164/168/171 MB/s 164/168/171 MB/s
Cache (MB) 64 64
Rotational speed (RPM) 7200 7200

According to WD, Black and RE drives should have the exact same performance. However, in our testing, we have found that WD's specifications really don't tell the whole story. We run and log a number of benchmarks (including hard drive performance) on all of our systems during the production process which gives us a very large number of system benchmarks to draw from. While the sequential and random read/write MB/s and random read IOPS results are always very close between Black and RE drives, we have found that RE drives consistently have much better random write IOPS than their Black counterparts.

Another interesting thing that we have found is that while the exact performance of Black drives varies due to different hardware and firmware revisions, RE drives have a locked configuration which results in more consistent performance between drives.

If you are interested in an example of the performance difference between Black and RE drives, take a look at the benchmarks below comparing a Black 2TB and RE 2TB drive on the new X99 platform using CrystalDiskMark:

Western Digital RE and Black CrystalDiskMark Western Digital RE and Black CrystalDiskMark IOPS


Reliability/Data Integrity

Reliability/Data Integrity Black 2/3/4 TB
(FZEX Series)
RE 2/3/4 TB
(FYYZ Series)
Load/unload cycles 300,000 600,000
Non-recoverable read errors per bits read <1 in 10^14 <10 in 10^16
(or <1 in 10^15)
MTBF (hours) Unlisted 1,200,000
AFR Unlisted .73%
Limited Warranty 5 year 5 year

A load/unload cycle is when the disk spins up its platter to get ready for operation. Typically this happens when you turn on a system, resume from standby, or when the drive has been idle long enough for the OS to power down the drive. While RE drives are rated for twice the number of load/unload cycles, the 300,000 cycles the Black drives are rated for is really quite a lot already. Even if you turn on/off your system or let it idle long enough to power down the drive 20 times a day, 365 days a year, the Black drives should still last for over 40 years.

The number of non-recoverable read errors per bits read is simply a metric of how often WD expects a read error to occur on the drive. Black drives are rated for 1 error in every 10^14 bits read and the RE drives are rated for 10 errors in every 10^16 bits read (which is the same thing as 1 error in every 10^15 bits read). 10^14 and 10^15 bits are huge numbers that are pretty hard to wrap your head around, so a better way to think of it is to convert the numbers from bits to terabytes. Doing that, the error rate becomes 1 error in 12.5TB read for the Black drives and 1 error in 125TB read for the RE drives. Either way, RE drives should have ten times less read errors than Black drives.

While the Black drives do not have a listed MTBF or AFR (Mean Time Between Failures and Average Failure Rate respectively), the RE drives are rated for 1,200,000 hours of enterprise-level usage. Both the Black and RE drives come with a 5 year warranty through WD.

Power Management

Power Management Black 2/3/4 TB
(FZEX Series)
RE 2/3/4 TB
(FYYZ Series)
Sequential read 9.5W 10.2W
Sequential write 9.5W 9.7W
Random read/write Unlisted 10.9W
Idle 8.1W 8.6W

From a power consumption standpoint, the RE drives use about .2-.7 more watts than the Black drives. This is not a significant amount, but it does mean that the RE drives should run a hair hotter than their Black counterparts.

Environmental Specifications (noise)

Environmental Specifications Black 2/3/4 TB
(FZEX Series)
RE 2/3/4 TB
(FYYZ Series)
Temperature - operating (°C) 5 to 55 5 to 55
Temperature - non-operating (°C) -40 to 70 -40 to 70
Shock - operating - 2 ms, write (Gs) 30 30
Shock - operating - 2 ms, read (Gs) 65 65
Shock - non-operating (Gs) 300 300
Acoustics - Idle 29 dBA 31 dBA
Acoustics - Seek (average) 34 dBA 34 dBA

For both the temperature limits and shock ratings the Black and RE drives are identical. In fact, the only difference between the two drive lines for these specifications is the idle noise levels. While the RE drives are rated to be 2dBA louder than the Black drives at idle, in our experience the difference is almost imperceptible. Neither of these drives are particularly quiet (WD Green and Red drives are much quieter), but unless you have a RE and Black drive side-by-side in a quiet environment, you are very unlikely to hear the difference.

Physical Dimensions

Physical Dimensions Black 2/3/4 TB
(FZEX Series)
RE 2/3/4 TB
(FYYZ Series)
Size - LxWxH (in.) 5.787x4x1.028 5.787x4x1.028
Weight 1.32/1.4/1.5 lb 1.55/1.66/1.66 lb

Finally, since both the Black and RE drives are standard 3.5inch drives they are both the same physical size. However, the RE drives do weigh more than the Black drives by as much as a quarter of a pound.


What it comes down to is that the WD RE drives have more advanced vibration protection with RAFF technology, support TLER (extremely useful for RAID arrays), are more reliable, and have much better random write IOPS than Black drives. On the other hand, they are slightly more expensive, use a little more power, and weigh a bit more.

In most situations the increased power draw and weight are likely non-factors. The price, however, is certainly a major consideration. However, our opinion the small price premium is very well worth all the advantages found in RE drives.

In the coming weeks, look for more and more of our certified systems to move from Black drives to RE drives. This is a pretty big move, and we would absolutely love to hear what you think about it. Let us know in the comments below!

Tags: Western Digital, WD, Black, RE

Would be great if you could include your recorded failure rates for each type of drive to see how they stack up in practice.

Posted on 2014-09-30 03:03:32

Right now, we don't have enough sales numbers for the RE drives for it to be significant. We've never been shy sharing failure rates, however, so we will definitely publish that information once we feel we have enough data.

Posted on 2014-09-30 16:30:32

Hmm... so I believe the real question boils down to is TLER going to create enough problems where the black drive or possibly the Red Pro drive would be a better options for everyone who cannot remove it.

Do you think the Red Pro or Black would be the better option because of this? Or is TLER is more of a side note?

Posted on 2016-05-22 08:32:04

TLER is very important if you are using a RAID, but we haven't found that it makes any difference if you are using the drive as a normal drive. It doesn't help, and as far as we can tell it doesn't hurt either. We use the RE drives a ton in our systems, and most of the time they are not in RAID. So far, we have had absolutely zero issues.

Posted on 2016-05-23 16:51:46

Awesome! Seems like the Re drives are the clear winner. Thanks.

Posted on 2016-05-24 06:22:09

If possible maybe changing
"While TLER is absolutely great if the drive is used in a RAID array, it is not useful (and could even be a negative) if the drive is simply a stand-alone drive. Luckily, WD has provided us with proprietary tools that allow us disable TLER on systems that do not have RAID arrays."

Seems like that is what is creating the confusion.

Posted on 2016-05-24 06:33:31

Oh, great call - I thought we had removed that already. Thanks for the catch!

Posted on 2016-05-24 18:03:41

If a drive fails and you need to recover data from it with ddrescue, TLER is a big advantage. If there're only a few bad sectors it doesn't matter, but if you're trying to recover data from a drive with lots of bad sectors, it can drag on for weeks or longer, if you don't have TLER.

In fact, I don't understand why the drive manufacturers don't have a no-retry read mode for data recovery. It would be trivial for them to implement, and it would make successful data recovery possible much more often. But TLER is better than nothing.

Posted on 2020-05-31 05:52:20

"Luckily, WD has provided us with proprietary tools that allow us disable TLER on systems that do not have RAID arrays."

Do you have a link to download the tools to disable TLER. Great article and I use the WD RE as stand alone but didn't know that disabling TLER would be a good think to do. Any help is appreciated!

Posted on 2014-12-06 19:54:56

Interesting.. I wonder if this tool would allow users to enable TLER on WD blacks? whatever the case the RE enterprise drives are the highest binned drives coming out of western digital factories and RAFF makes them more suitable for 24/7 operations

Posted on 2014-12-17 12:29:30
Anonymous Frank

You don't need to use the proprietary tools. It's almost certainly configured using some ATA command. The hdparm utility (which is fully open source, not proprietary) in Linux is able to mess with these.

Wait, I just looked it up... https://en.wikipedia.org/wi...
tl;dr modern RE drives have it locked on. You cannot disable it.

Posted on 2016-02-25 11:51:42

I just read that the TLER can not be disabled on the RE drives. http://wdc.custhelp.com/app...

Posted on 2015-03-13 19:18:47
James Warne

Do you guys know if the WD Black 2.5's have TLER support or the option to turn it on? It seems 7200 RPM disks with TLER are significantly more expensive than the non TLER disks.

Posted on 2016-06-01 02:42:32

No, TLER is a feature built into the drives that are designed to be used in RAID arrays. So, RE, Red, and Purple are the drives you would want to look at if you need TLER support.

Posted on 2016-06-01 16:22:56

"Doing that, the error rate becomes 1 error in 12.5TB read for the Black drives"
Does it means that a 2TB black drive shouldn't be completely copied more than 6 times?

Posted on 2016-12-10 19:50:35

I've been running WD RE4 HDD's since 2012, the first time as a 500GB single drive system only, now as a Data drive paired with various SSD's. Other than a single bad sector on the first one purchased (still runs great otherwise!), have had just one issue, had to remove one 500GB from a Linux desktop because it was reporting the HDD as being in RAID, even though it wasn't. So swapped for a Seagate laying around & placed the affected RE4 in a HDD only system, no issues. For the record, have never used RAID, because haven't needed the feature yet, although won't rule out for any future needs.

It could had been in my case, that most of my RE4's (have nearly a dozen in usage) were 'new pulls' from servers with 0 minutes, probably replaced with larger models, from a reputable eBay supplier who buys these drives in bulk (may have small a HP, Dell, IBM/Lenovo sticker on front). Even the one used 1TB RE4 with over 10,000 hours of usage has performed flawlessly & has been in no less than five PC's.

Going back to why I chose the RE4 over the Caviar Black, Newegg had a promo on the first purchased, what stood out was the 64MB cache, versus 32MB for the WD Caviar Black already owned. In my tests, first on SATA-2 computers, later SATA-3, the RE4 edged out the Caviar Black (now in an aluminum backup enclosure), has been very reliable, makes no more audible noise & has dual processors. I'll continue to purchase the WD RE4 from the same seller for as long as he has these based on need.

Have more recently purchased two 2TB WD Gold HDD, I presume to be the replacement for the RE4, with SATA-3 & a 128MB cache, reads & writes at close to 200MB/sec, of which the latter is close to the speed of my first SSD purchased in 2012 & before the first RE4, a 128GB Crucial m4. Which was faster than platters of it's day, although nowhere as fast as my 2nd SSD purchased 5-6 months later, an underrated 180GB Intel 330 that to this day, still reads & writes at over 500MB/sec if on an Intel SATA-3 MB. So while I'll continue to purchase RE4's while available as new pulls for storage, will also likely be getting the WD Gold for newer builds for the performance boost & for the speed of SATA-3.

Bottom line, the RE4 is still a great drive and I have zero regrets over choosing versus the one Caviar Black which had to be replaced (RMA) in under a year. Glad that I noticed the 500GB RE4 on promo when HDD pricing in general was still high in cost, otherwise may had never known of the outstanding series.

EDIT: I may have done one thing that's extended the life of all of my drives, and that's using the HIPM-DIPM registry download found on many Tech forums, and set the mode to Active and at 'Turn hard disk after' 0 minutes, which shows as 'Never' once reopened. This saves on a lot of unnecessary start/stop cycles, regardless of brand or model drive, those with lower end models may see the most benefit. The result is a drive that shows the actual startup/shutdown cycles near the same as load/unload cycles, rather than hundreds by the day.


Posted on 2018-02-18 21:36:32