WD Introduces Red: NAS Optimized HDD Line
by Jason Inofuentes on July 10, 2012 8:13 AM EST
WD did everyone a favor when they reorganized their products under color-coded branding a few years ago. With the Blue (mainstream), Green (quiet and cool) and Black (performance) lines well laid out, consumers have a much easier time picking out the right drive for their application, rather than poring over spec sheets and complex model numbers. And now there's another line to add to that list: Red. Designed specfically to be used in 1-5 bay NAS devices, the Red line has hardware and software features that make it suited for that particular climate, while delivering impressive performance and reliability. WD has worked with major NAS manufacturer's to ensure compatibility with as many common NAS products as possible, and has a list of the tested devices here.
The secret sauce in these drives is the firmware, or as WD is calling it NASware. NAS devices in the home are often used for bulk storage of media, they may have some shared documents and be used as back-ups, too; but they're most often used to store movies, music and images. ATA streaming command is featured in NASware, to alter the behavior of the drive while streaming media, in an effort to ensure smooth playback, even while serving mutliple streams. They've also included error correction optimizations to prevent a drive from dropping out of a RAID array while it chases down a piece of corrupt data. The downside is that you might see an artifact on the screen briefly while streaming a movie, the upside is that you won't have playback pause for a few seconds, or for good depending on your configuration, while the drive drops off the RAID to fix the error.
Then there's the matter of performance. With quoted performance of around 150 MB/s these drives are nudging into Black territory. WD's new balance mechanism contributes to this. By actively balancing the drive during use there's no need to slow the drive down to prevent damage, so performance remains high. There's also a reported power savings, which WD says will make up the price delta for these drives over the rest of the line through your power bill. Speaking of price, the MSRP for the 3.5" 1TB, 2TB and 3TB drives are $109, $139 and $189, respectively. And these drives are available at your favorite e-tailer starting today. Ganesh is patiently awaiting our review samples so he can put them through the ringer and see how they do.
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Metaluna - Tuesday, July 10, 2012 - link
Do you know if ZFS can reconstruct a bad sector on the fly and return it to the application right away, or will it hang for the full 15+ seconds?It sounds like the only way Red drives can avoid the TLER issue is if you have:
A) An app running server-side that knows when it's trying to stream video or audio
B) The app knows how to issue the ATA streaming commands, and
C) the OS has a driver and RAID controller that both support passing the command through to the array.
The odds of all these conditions occurring on any ZFS-supporting OS any time soon are essentially nil :(.
Solandri - Tuesday, July 10, 2012 - link
In redundant arrays like RAID-Z (like RAID 5/6) and mirrors, the filesystem just corrects the error from parity as OP said. So it's instantaneous.On striped arrays you have the option of specifying a zpool should store x copies of each file. While this won't protect against a disk failure, it does protect against sector failures. And like the redundant case, errors are detected and corrected from the alternate copy instantaneously.
You're also supposed to scrub the ZFS drives once a week or so. That double-checks the checksums of all the files and corrects any errors that may have developed from bit rot. So in most cases any errors will be caught before the data is needed that instant.
tuxRoller - Tuesday, July 10, 2012 - link
I know bit rot protection is a big feature of zfs but do you know how infrequently it happens? As I recall, it has two causes: cosmic rays (which are extremely low flux, at least of the type we are talking about), and spontaneous thermodynamic field inversion (from the name alone you can guess how frequently that must happen).BTW, I'm not trying to slam the feature, or zfs, I just think zfs has other features worth mentioning first.
chadwilson - Monday, July 16, 2012 - link
It happens more frequently than you think. When you look at the specs on drives, they have not changed much in the past decade, but the density has significantly increased. There was a study done by Google and they showed at 1TB, you would see on average 1 bit flip per drive per year. Not so important for your blu-ray collection. Significantly so for encrypted customer data :)dealcorn - Saturday, August 18, 2012 - link
" This behavior is unacceptable for anything used in RAID."Sometimes that is true and sometimes it is not. The issue involves conflicting parameters between the RAID controller and the drive. Software RAID such as mdadm and ZSF typically works OK with, say, a SAS/SATA controller configured in IT mode to provide SATA ports because there is no conflict to be had between the drive and the controller. Hardware based RAID solutions commonly cause the problem,
The "OK" part means its works faster if you use the software and CPU to recover the data without waiting for the drive to sort out it's issue or not. Limiting the drive's error recovery tine means better performance under error conditions with software RAID.
mcnabney - Tuesday, July 10, 2012 - link
In almost every installation a NAS is going to be bottlenecked by the gigE network connection - so any speeds beyond about 120MB/s is going to be complete overkill. I do like the power and connectivity benefits of the device.Otherwise, the Green drives, which transfer 100-110MB/s on sequential data (media files), are still a better option with a lower price point, low heat, low power consumption, and performance that best fits the limitations of a NAS.
JasonInofuentes - Tuesday, July 10, 2012 - link
I agree that the NAS bottleneck is the gigE network, even if you could squeeze in dual-gigE. We're waiting to see whether there's any value in the added transfer speed in managing the RAID. Certainly if you add a drive or are recovering from a failure the added speed could hlep speed that process along. And, if the speed comes free with the power benefits and NASware, then it certainly won't hurt.eanazag - Tuesday, July 10, 2012 - link
There are some NAS devices with 10GigE interfaces or upgrades. Unfortunately, getting a 10 GigE switch is not so cheap, and neither are the interface cards. It can be done if you have the money and need it.mcnabney - Wednesday, July 11, 2012 - link
A NAS isn't used for high speed. If you need high speed get a thunderbolt-connected SSD array to sit next to your computer. The purpose of a 'typical' NAS is to reliably hold data with speed as a tertiary concern. Want to attract my attention - increase the MTBF.Solandri - Tuesday, July 10, 2012 - link
Bear in mind that the advertised sequential read/write speeds are the max you'll ever see - for data written on the outermost platters. HDDs typically have about a 2:1 ratio in radius between the outermost and innermost platters, so data on the innermost platters will have sequential read/write speeds about half that.So when you see a green drive advertised as 110 MB/s, it will actually deliver 55-110 MB/s in real-world use. I have 110 MB/s green drives in my NAS. And the average throughput I see writing large files to them is indeed 75-80 MB/s. That's fine for me, but for other applications I can see the extra 35 MB/s (avg) of these red drives to saturate gigabit being important.