For years, a visitor to a tech forum would find a veritable flood of posts in the NAS section asking which desktop HDD's are best for NAS usage. Surprisingly, many of these posts from those in the hunt for reliable and reasonably priced HDD's weren't always 'typical' consumers, they also encompassed many in the SMB and SOHO environment. While higher-end nearline and enterprise HDD's have always been advised for NAS usage, many balked at the high price and actively sought out cheaper alternatives. Finding a desktop HDD that will work in any one of the hundreds of different NAS models can become somewhat of a gamble. Many times users will find a HDD that will simply plug in and work, but then become plagued by issues with repetitive unnecessary RAID rebuilds.
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This stems from the TLER (Time Limited Error Recovery) settings on common desktop HDDs. While TLER comes under different names depending upon the manufacturer of the HDD, the basic premise is the same.
Even during normal operation, HDD's are prone to errors when reading and writing data to the platters. There are a number of techniques utilized by the HDD to combat and repair these errors.
During the frantic attempt to correct an error, the HDD stops communicating with the NAS. If the repair takes more than seven seconds, the vast majority of RAID systems will drop the HDD from the array. Once dropped the user has to withstand a long rebuild period, during which the performance of the NAS is greatly impacted. There really aren't many storage solutions slower than a degraded RAID 5, and for home users this can become an exercise in futility.
For those relying upon a NAS in an SMB or SOHO environment (such as a dentist, veterinarian, or lawyer's office), this slow performance can actually result in a massive impact upon their ability to conduct work in a timely fashion. Another TLER error during the rebuild period can result in a total loss of all the data stored on the NAS, turning an inconvenience, into a disaster. Enter the new NAS HDD's from Seagate. These HDD's, like the ones offered by WD, are designed to combat the TLER problem head on. If the error recovery takes longer than the appointed time, a NAS HDD can actually communicate with the RAID code, informing it that there is a problem with data recovery. This hands the problem off to the NAS, allowing the NAS to repair the error itself.
The NAS will perform a targeted RAID rebuild, only repairing the effected data. This results in reliable and efficient performance in RAID environments. The Seagate NAS HDD's are qualified with all major NAS vendors, and feature other enhancements to optimize them for NAS usage. NASware is a suite of firmware features that improves drive reliability, provides vibration reduction, and delivers optimized power settings. Vibration from other HDDs in a multi-bay NAS can introduce performance and reliability concerns. This is combated with a dual plane balance system to provide less vibration than typical desktop HDD's.
The lower thermal threshold of a NAS HDD also protects the inner workings of the NAS from excessive heat, and reduces the amount of fan noise in models with self-adjusting fans.
Considering the fact that network-attached storage (NAS) use is growing at an alarming rate, it didn’t surprise us much last summer when WD released its, but it did make us question, “what took so long?” A NAS-specific hard drive might seem like a gimmick at first, but there are important differences over other low-powered drives that makes them the better and safer solution. The most important tweak in NAS drives is the reduction of the timeout value for error correction. Low-power drives, such as WD’s Green, for example, are not designed to work with RAID controllers, which are what handles the error-correction in NAS solutions. Thus, if a hard drive and RAID controller are battling each other for error-correction, one can cancel out the other, and the drive can potentially drop from the RAID – that’s the beginning to a bad day. The unfortunate thing is that these caveats weren’t properly understood when green drives first hit the market. A couple of months ago, a host I had a couple of services with lost a ton of my data (nothing important).
In discussing the problem with the company later, I discovered it had been using WD’s Green drives in its servers. After a couple of years, and out of nowhere, there was a problem, and a lot of data was lost. This isn’t WD’s fault, of course green drives are simply not meant for server use. My host was looking for the cheap way out, and it eventually hit it where it hurts. The issue could have been avoided with NAS or enterprise drives. Upon their release, WD’s Red capped at 3TB (1 and 2TB models were also available).
I considered it to be a little strange that a 4TB model wasn’t made available at the time, but didn’t rant about it too much since I figured it was right around the corner. It wasn’t until just a couple of months ago that we realized the reason why: WD’s enterprise-bound Se fills the 4TB void. While WD’s Se series is the better of the two (vs. Red), it’s more expensive. For a consumer wanting to make the most of their NAS, cheaper options are likely to be considered – there’s redundancy in place, after all, so if a 2-year warranted drive dies a little too soon, it can be easily replaced with no data loss. From that standpoint, Red is ideal, but with the lack of a 4TB option, some consumers might not have been too pleased. Well, Seagate noticed that void and has come to fill it, and interestingly, while WD’s Red series includes a 1TB option, Seagate’s “NAS HDD” series does not.
We can’t imagine that 1TB options for NAS use is that popular anyway. Here’s a rundown of Seagate’s current desktop and enterprise line-up: Density Speed Warranty Usage Price Desktop HDD 1TB – 4TB 5,900 7,200 1 2-year Consumer $175 (4TB) Desktop SSHD 2 1TB – 2TB 7,200 + 8GB SLC 3-year Consumer $??? Enterprise Capacity 1TB – 3TB 7,200 5-year Enterprise $370 (4TB) Enterprise Value 1TB – 3TB 7,200 3-year Enterprise $190 (3TB) Terascale HDD 4TB 5,900 3-year Enterprise $335 (4TB) NAS HDD 2TB – 4TB 5,900 3-year NAS $210 (4TB) All speeds are in RPM (rotations per minute).
All drives include 64MB of cache (Enterprise Capacity (Constellation ES.3) includes 128MB). Pricing is based on stable trends across Amazon and Newegg. 1 4TB model is 5,900 RPM; rest are 7,200 RPM. 2 Cannot be found at retail; for OEMs only. For NAS compatibility, go (click on “Features”).
Would you believe that this single table took me longer than an hour to create? That’s entirely thanks to how difficult Seagate makes it to find certain information. Transparency clearly isn’t the company’s strong point. That aside, I found that understanding Seagate’s line-up was much more difficult than WD’s – I guess I kind of like the simplified naming scheme on the WD side (Red, Green, Blue, Black, Se, Re) better than Seagate’s, which sometimes doesn’t even stay consistent with itself. Did you know that “Enterprise Capacity” is being sold as Constellation ES.3 virtually everywhere? Seems needlessly complex. The best-comparable drive to the NAS HDD in Seagate’s own line-up is Desktop HDD – at least if we’re talking about the 4TB model.
While all three NAS HDD densities are spec’d at 5,900 RPM, only the 4TB model in the Desktop HDD series is. Similar to what we saw in WD’s line-up, the NAS variant costs a bit more TB for TB, but it has the worthwhile perk of having another year added to its warranty (3 vs. NAS HDD is recommended by Seagate for those at home, running a NAS with 1 – 5 drives, while Constellation CS drives are better recommended for small business, where 6 – 8 bay NASes might be used. For mission-critical NAS-use, such as with surveillance, Constellation ES.3 drives are Seagate’s recommendation (as would be ours, or WD’s Re drives). Hard drives from different vendors might have various tweaks to their formula, but it’s safe to say that WD’s NAS drive and Seagate’s NAS drive are not going to be too different for the average consumer. So, pricing comes into play. Where do we stand?
1TB 2TB 3TB 4TB Seagate NAS HDD N/A $124 ($62/TB) $156 ($52/TB) $210 ($52.5/TB) WD Red $80 ($80/TB) $105 ($52.5/TB) $146 ($48.66/TB) N/A Pricing information courtesy of Amazon and Newegg (08/11/13). Best (stable) prices selected only. For a 4TB NAS offering, there’s just one option, so that will rule WD out for some people (WD’s enterprise Se 4TB is $280). Perhaps due to the fact that they’ve been on the market for a year, WD’s Red costs a bit less than Seagate’s NAS HDD for the 2TB and 3TB options (saving $19 and $10, respectively). We won’t go into each and every feature the NAS HDD series includes, because little has changed over the years (that the companies can tell us, at least). NASworks is the leading feature on this particular series, which as we mentioned before tweaks the error correction to make sure it never becomes a problem, reduces vibration and includes more advanced power profiles. All very good stuff.
While this won’t affect the home user much, it’s worth quickly covering what the NAS HDD series lacks vs. Performance is at the top of the list, with a reported 140MB/s for NAS HDD and 160MB/s+ for Constellation. NAS HDD also lacks an internal secure erase (important for truly sensitive data), lacks the self-encryption of the Constellation ES.3 series and doesn’t have quite as robust vibration-reduction solutions. Again though, nothing here is likely to affect a home user, especially overall performance, given 140MB/s exceeds your Gigabit network’s peak of 125MB/s. On the topic of performance, let’s see how Seagate’s NAS HDD fares there.