Picking A Hard Drive For Your NAS: New Green Beats Old Speed

Pros And Cons Of Going Green?

Reasons to go Green

As you can see in the table on the previous page, the newer Samsung HD103SI draws about three watts less power than the older HD321KJ. While this is partly due to the slower rotation speed of its 5,400 RPM spindle, other technological advances in hard drive manufacturing also contribute to the lower power consumption.

When a computer or NAS is equipped with a single hard drive, a power consumption difference of only three watts is negligible. However, that should be the exception for NAS devices. Loaded with the four drives our testbed system can house, the difference jumps into the two-figure range. And that can definitely make a difference when the time comes to pay your electric bill. A welcome side effect is that the NAS stays cooler as well, which also means that the unit runs quieter since its fans can spin more slowly.

Those worried about having to pay a premium for a more eco-friendly hard drive model can relax, as disks with a spindle speed of “only” 5,400 RPM tend to be slightly less expensive than faster drives aimed at the performance segment.

Does Eco mean Lower Performance?

But what about performance? Is there a penalty for using an eco-friendly drive in a NAS device? As mentioned above, when we take a look at the components that make up a typical NAS, we find that the hard drives are not actually the bottleneck. Rather, it’s often the NAS’ RAID engine.

To keep their appliance's prices at an affordable level, manufacturers often forego the inclusion of a dedicated processor for this task, instead letting the NAS’ host processor handle the burden of XOR calculations required for RAID levels 5 and 6. On the downside, this method is much less efficient than having a dedicated RAID chip. As a result, data throughput is highly dependent on the processor that a NAS uses.

Marcel Binder
  • Is it a good comparison between 320 GB drives and 1 TB ones? Of course de 1 TB will perform better: much higher data density means less movement of heads and platters for the same amount of data. Gotta be faster. Nothing to do with the enclosure.

    Also I would like to mention from my own experience that heat can be a problem. I have a D-Link DNS323 and it cannot handle two server edition WD drives - it overheats.

    - Bertus.
  • evongugg
    If you buy a NAS, it's better to use the recommended drives, which have been put through hard tests.
    Other drives may experience RAID problems, burnout problems, etc.
    If you want to salvage a NAS hard drive, you may be dealing with a Linux type partition.
  • Weird concept to compare an "old" performance drive with a new eco drive, where by default the new eco drive is outperforming the old performance drive in all categories.
    What is the expected result? Yes, we guessed right, the new eco drive is outperforming the old performance drive in a NAS environment.
    Unfortunately that comparison does not allow any conclusion whether a NAS needs a performance drive or not, it only tells us that a new eco drive is better than an old performance drive.
  • awaken688
    Totally agree with "theaxe" on this one. Not sure what this proved other than if you choice is an old performance drive vs. a new green one, choose the green one. Show me the WD 1TB Caviar Black vs. an equivalent "green" 1TB drive and then we can see more of a comparison that means something.
  • cknobman
    good thing we have the comments section so I dont wast my time reading a pointless article. first thought is "why in the f would you compare a 320gb to a 1gb?" reading the comments let me know my thought is right and not to waste time reading a pointless article.
  • chunkymonster
    Our comparison showed that the difference in write performance between faster and slower spinning hard drives is minimal to nonexistent when they are used in a NAS. Instead, the NAS’ RAID engine becomes the limiting factor.
    Ok, I can understand the RAID engine being the limiting factor when using off the shelf NAS solutions, especially considering most off the shelf NAS solutions use software RAID. But, would a 5400RPM drive become the limiting factor, compared to a 7200RPM, when using a hardware RAID solution like an Areca, 3Ware, or HighPoint controller card? Any guesses?
  • davidhbrown
    I've been reflexively buying 7200RPM drives for everything (notebooks, NAS, desktops) for so long now, that just the *concept* of the article is a useful reminder that in some settings, other issues might be important. Too bad the specific comparison may be flawed, but it's not like exactly that hardware is going to be relevant in six months anyway.
  • Even with a 10 watt difference, the electricity savings is negligible. At the nation average of 12 cents per kWh, using 10 less watts 24/7 for a year works out to be a whole $10.50. On the year. Less than $1 a month. A far cry from what the article stated: "the difference jumps into the two-figure range. And that can definitely make a difference when the time comes to pay your electric bill" I'll take that 88 cents I save a month and go buy...wait, what can you get for 88 cents these days?
  • farrellj
    Just one thing...many consumer NAS boxes run a cut-down form of Linux...and Samba! And that makes it much more stable than some proprietary software that hasn't been as extensively tested as Linux/Samba has.
  • farrellj
    Just found out...the Synology DS409+ does use Linux!