Feature Set Comparison

Enterprise hard drives come with features such as real time linear and rotational vibration correction, dual actuators to improve head positional accuracy, multi-axis shock sensors to detect and compensate for shock events and dynamic fly-height technology for increasing data access reliability. For the WD Red units, Western Digital incorporates some features in firmware under the NASware moniker. We have already covered these features in our previous Red reviews. These hard drives also expose some of their interesting firmware aspects through their SATA controller.

A high level overview of the various supported SATA features is provided by HD Tune Pro 5.50

The HGST Ultrastar He6 supports almost all features (except for TRIM - this is obviously not a SSD - and Automatic Acoustic Management - a way to manage the sound levels by adjusting the seek velocity of the heads). The Seagate Enterprise Capacity drive avoids the host protected area and device configuration overlay, as well as the power management features. APM's absence means that the head parking interval can't be set through ATA commands by the NAS OS. Device Configuration Overlay allows for the hard drive to report modified drive parameters to the host. It is not a big concern for most applications. Coming to the WD Red, we find it is quite similar to the Ultrastar He6 in the support department, except for the absence of APM (Advanced Power Management).

We get a better idea of the supported features using FinalWire's AIDA64 system report. The table below summarizes the extra information generated by AIDA64 (that is not already provided by HD Tune Pro).

Supported Features
  WD Red Seagate Enterprise Capacity v4 HGST Ultrastar He6
DMA Setup Auto-Activate Supported, Disabled Supported, Disabled Supported, Disabled
Extended Power Conditions Not Supported Supported, Enabled Supported, Enabled
Free-Fall Control Not Supported Not Supported Not Supported
General Purpose Logging Supported, Enabled Supported, Enabled Supported, Enabled
In-Order Data Delivery Not Supported Not Supported Supported, Disabled
NCQ Priority Information Supported Not Supported Supported
Phy Event Counters Supported Supported Supported
Release Interrupt Not Supported Not Supported Not Supported
Sense Data Reporting Not Supported Supported, Disabled Supported, Disabled
Software Settings Preservation Supported, Enabled Supported, Enabled Supported, Enabled
Streaming Supported, Disabled Not Supported Supported, Enabled
Tagged Command Queuing Not Supported Not Supported Not Supported

Interesting aspects are highlighted in the above table. While the two enterprise drives support the extended power conditions (EPC) extensions for fine-grained power management, the Red lineup doesn't. NCQ priority information adds priority to data in complex workload environments. While WD and HGST have it enabled on their drives, Seagate seems to believe it is unnecessary. The NCQ streaming feature enables isochronous data transfers for multimedia streams while also improving performance of lower priority transfers. This feature could be very useful for media server and video editing use-cases. The Seagate enterprise drive doesn't support it, and, surprisingly, the Red seems to have disabled it by default.

6 TB Face-Off: The Contenders Performance - Raw Drives
Comments Locked


View All Comments

  • NonSequitor - Thursday, July 24, 2014 - link

    So something isn't adding up here. I have a set of nine Red 3TB drives in a RAID6. They are scrubbed - a full rebuild - once a month. They have been in service for a year and a half with no drive failures. Since it's RAID6, if one drive returns garbage it will be spotted by the second parity drive. Obviously they can't be returning bad data, or they would have been failed out long ago. The array was previously made of 9 1TB Greens, scrubbed monthly, and over two and a half years I had a total of two drive failures, one hard, one a SMART pre-failure.
  • asmian - Friday, July 25, 2014 - link

    Logically, I think this might well be due to the URE masking on these Red drives - something the Green drives weren't doing. You've been lucky that with a non-degraded RAID6 you've always had that second parity drive that has perhaps enabled silent repair by the controller when a URE occurred. I've been pondering more about this and here's what I have just emailed to Ganesh, with whom I've been having a discussion...


    On 24/07/2014 03:45, Ganesh T S wrote:
    > Ian,
    > Irrespective of the way URE needs to be interpreted, the points you
    > raise are valid within a certain scope, and I have asked WD for their
    > inputs. I will ping Seagate too, since their new NAS HDD models are
    > expected to launch in late August.

    Thanks. This problem is a lot more complicated than it looks, I think, and than a single URE figure might suggest. But the other "feature" of these Red drives is also extremely concerning to me now. I am a programmer and often think in low-level algorithms, and everything about this URE masking seems wrong in the likely usage scenarios. Please help me with my logic train here - correct me if I'm wrong. Let's assume we have an array of these Red drives. Irrespective of the chance of a URE while the array is rebuilding or in use, let's assume one occurs. You have stated WD's info that the URE is masked and the disk simply returns dummy info for the read.

    If you were in a RAID5 and you were rebuilding after you've lost a drive, that MUST mean the array is now silently corrupted, right? The drive has masked the read failure and reported no error, and the RAID controller/software has no way to detect the dummy data. Critically, having a back-up doesn't help if you don't know that you NEED to repair or restore damaged files, and without a warning, due to simple space contraints a good backup will likely be over-written with one that now contains the corrupted data... so all ways round you are screwed. Having a masked URE in this situation is worse than having one reported, as you have no chance to take any remedial action.

    If you are in RAID6 and you lost a drive, then you still have a parity check to confirm the stripe data with while rebuilding. But if there's a masked URE and dummy data, then how will the controllers react? I presume they ALWAYS test the stripe data with the remaining parity or parities for consistency... so at that point the controller MUST throw a major rebuild error, right? However, they cannot determine which drive gave the bad data - just that the parity is incorrect - unless it's a parity disc that errored and one parity calculates correctly while the other is wrong. If they knew WHICH disc had UREd then they could easily exclude it from the parity calculation and rebuild that dummy data on the fly with the spare parity, but the masking makes that impossible. The rebuild must fail at this point. At least you have your backups... hopefully.

    Obviously the above situation will also be the same for a RAID5 array in normal usage or a degraded RAID6. Checking reads with parity, a masked URE means a failure with no way to recover. If you have an unmasked URE at least the drive controller can exclude the erroring disc for that stripe and just repair data silently using the remaining redundancy, knowing exactly where the error has come from. After all, it's logically just an EXPECTED disk event with a statistically low chance of happening, not necessarily an indication of impending disk failure unless it is happening frequently on the same disc. The only issue will be the astronomically unlikely chance of another URE occurring in the same stripe on another disc.

    Fundamentally, a masked URE means you get bad data without any explanation of why a disc is returning it, which gives no information to the user (or to the RAID controller so it can take action or warn the user appropriately). For me, that's catastrophic. It all really depends on what the controllers do when they discover parity errors and UREs in rebuild situations and how robust their recovery algorithms are - an unmasked URE does not NEED to be a rebuild-killer for RAID6, as thank G*d you had a second redundancy disc...

    Anyway, the question will be whether these new huge drives will, as you say, accumulate empirical evidence from users that array failures are happening more and more frequently. Without information from reviews like yours that warn against their use in RAID5 (or mirrors) despite the marketing as NAS products, the thought-experiment above suggests the most likely scenario is extremely widespread silent array corruption. I stand by my comment that this URE masking should be a total deal-breaker in considering them for home array usage. Better a disk that at least tells you it's errored.
  • NonSequitor - Tuesday, July 29, 2014 - link

    That still doesn't add up - there are no unmasked UREs in my situation, as I'm using Linux software RAID. It is set to log any errors or reconstructions, and there are literally none. One of these arrays has a dozen scrubs on it now with no read errors whatsoever.
  • m0du1us - Friday, July 25, 2014 - link

    @asmian This is why we run 28 disk arrays minimum for SAN. If you really want RAID6 to be reliable, you need A LOT of disks, no matter the size. Larger disks decrease your odds of rebuilding the array, that just means you need more disks. Also, you should never build a RAID6 array with less than 5 disks. At 5 disks, you get no protection from a disk failure during rebuild. At 12 disks, You can have 2 spares and 2 failures during rebuild before loosing data.
  • NonSequitor - Friday, July 25, 2014 - link

    Your comment makes no sense. A five disk RAID-6 is N+2. A 28 disk RAID-6 is N+2. More disks will decrease reliability. Our storage vendor advised keeping our N+2 array sizes between 12 and 24 disks, for instance: 12 disks as a minimum before it started impacting performance, 24 disks as a maximum before failure risks started to get too high. Our production experience has borne this out. Bigger arrays are actually treated as sets of smaller arrays.
  • LoneWolf15 - Friday, July 25, 2014 - link

    asmian, it totally depends on what you are building the array for, and how you are building it.

    Myself, I'd use them for home or perhaps small business, but in a RAID 10 or RAID 6. Then I'd have some guaranteed security. That said, if I needed constant write performance (e.g., multiple IP cameras) I'd use WD RE, and if I wanted enterprise level performance, I'd use enterprise drives.

    That, and I realize that RAID != backup strategy. I have a RAID-5 at home; but I sure as heck have a backup, too.
  • tuxRoller - Monday, July 21, 2014 - link

    Hi Ganesh,

    Would you mind listing the max power draw of these drives? That is, how much power is required during spin-up?
  • WizardMerlin - Tuesday, July 22, 2014 - link

    If you're not going to show the results on the same graph then for the love of god don't change the scale of the axis between graphs - makes quick comparison completely impossible.
  • ganeshts - Tuesday, July 22, 2014 - link

    I have tried that before and the problem is that once all the drives are on the same scale, then some of them become really difficult to track absolute values across. Been down that road and decided the issues it caused are not worth the effort taken for readers (including me and my colleagues) to glance right and left on the axes side to see what the absolute numbers are.
  • Iketh - Tuesday, July 22, 2014 - link

    what? why would they become difficult to "track absolute values" ??

Log in

Don't have an account? Sign up now