The market for network-attached storage units has expanded significantly over the last few years. The rapid growth in public cloud storage (Dropbox, OneDrive, Google Drive and the like) has tempered the expansion a bit amongst consumers who are not very tech-savvy. However, the benefits provided by a NAS in the local network are undeniable, particularly when complemented with public cloud services. Enterprise users obviously need NAS units with different performance and feature requirements. Our previous NAS reviews have focused more on the performance aspect. With feature set and ease of use becoming important across all market segments, we believe that a qualitative evaluation of the different commercial NAS operating systems is needed to educate consumers on the options available.


Commercial off-the-shelf (COTS) NAS operating systems are popular across a wide range of market segments - business and enterprise users (including those with dedicated IT staff) prefer to have plug-and-play storage units that don't need much babysitting, while the average consumer often wants a media-centric unit without the hassle of re-purposing an old PC or building a file server from scratch. This regularly-updated piece will take a look at the features and usability of the currently popular COTS NAS operating systems.

The following NAS vendors / operating systems are currently covered in this article:

  1. Asustor [ ADM 2.6.5R9N1 ]
  2. Netgear [ ReadyNAS OS 6.6.0 ]
  3. QNAP [ QTS 4.2.2 ]
  4. Synology [ DSM 6.0.2-8451 Update 3 ]
  5. Western Digital [ My Cloud OS 2.21.19 ]
  6. ZyXEL [ FW v5.20(AATB.0) ]

Different vendors cater to different market segments - both in terms of hardware and software features. For example, Asustor, Netgear, QNAP and Synology have units ranging from 2-bay desktop models targeting the average home consumer to 12-bay rackmounts targeting SMBs and SMEs. Western Digital has only desktop units- 1- and 2-bay models targeting entry level users, and multiple 2- and 4-bay models targeting experts, professionals and business users. ZyXEL, on the other hand, focuses on only one market segment - the average home consumer. Every vendor other than ZyXEL in the list above carries both ARM- and x86-based solutions. ZyXEL has only ARM-based solutions in their lineup. The choice between ARM and x86 has to be made by the end-user depending on the requirements (number of users, transcoding support etc.). This piece is not meant to provide inputs on the hardware choice, though we will briefly touch upon how the OS features might vary based on the platform. The hardware currently used to test out the various OS features are tabulated at the end of this section.

Security has turned out to be a very important concern for equipment connected to the network, particularly those exposed to the Internet. Therefore, frequent updates are needed even in the NAS firmwares to handle vulnerabilities that get exposed from time to time. The release date of the latest firmware is also a measure of the commitment of the NAS vendor to their consumers.

Most COTS NAS operating systems are based on Linux, and utilize software RAID (mdadm) with the stable ext4 file system. Recently, btrfs has also become popular in this space. ZFS, due to its resource-hungry nature, has been restricted to units targeting enterprise users. DIY consumers can also get a taste of it using open-source BSD-based operating systems such as FreeNAS.

The following table provides the essential information discussed above in a easy to compare manner.

NAS Operating Systems Evaluation - Comparison Details
Firmware Version ADM 2.6.5R9N1 ReadyNAS OS 6.6.0
Firmware Release Date October 3, 2016 September 29, 2016
OS Kernel Linux 4.1.0 Linux 4.1.30
File System ext4 btrfs (Customized)
Evaluated Hardware 10-bay AS6210T 4-bay ReadyNAS RN214

This piece focuses on the core user-facing aspects of COTS NAS systems. These include the setup process and the quality of the user interface. Storage management and configurable services are the next topic. An overview of user management is followed by discussion of the networking features available in each OS.

Most NAS operating systems have feature parity in terms of core features. However, as we shall see at the end of this piece, there is a difference in ease of use which make some vendors stand out of the crowd. These vendors also try to differentiate with value-added services such as media servers, surveillance (IP camera) support, cloud features and other such features. They will be covered in detail in a follow-on article.

Setup Process and User Interface
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  • cdillon - Monday, November 14, 2016 - link

    I meant to say "data and metadata check for ZFS" above, because it does both by default. You can turn off data checksums in ZFS just as easily as you can change the checksum algorithm, but can never turn off metadata checksums. ZFS will also never store less than 2 copies of all metadata (optionally more), giving you built-in redundancy in that respect, even in single-disk setups. This is one of several reasons that ZFS doesn't have and doesn't need a "fsck" utility, because the filesystem integrity is baked in to the design.
  • tuxRoller - Thursday, November 17, 2016 - link

    Btrfs has actually supported sha256...TWICE. The first time was back during early btrfs development and then they removed it because of how slow it was. It was submitted in 2014 by a oracle dev but not merged because they want a general solution, and, potentially, much more flexibility (using the crypto API instead of having to maintain their implementations;per file hash algorithm (so, some files could use a stronger hash than others); different hash functions for data and metadata (metadata is limited to 256 while data doesn't really have a limit))
    It's been percolating its way towards the kernel but it's not seen as a huge priority because: 1) there've been very few incidences of corrupt blocks passing ("crc32's error rate works out to one false positive per dozen megabytes *of random errors*--- that's a lot of errors, even talking into consideration CERN's data), 2) they already use sha256 for dedup (both in and out of band, though groundwork has been laid to make that pluggable as well)." target="_blank" rel="nofollow">" target="_blank" rel="nofollow">" target="_blank" rel="nofollow">" target="_blank" rel="nofollow">
  • ghostbit - Monday, November 14, 2016 - link

    Nah. I am very happy with the Web interface and iOS apps Synology offers along with a sleek and small low-power chassis.

    But I guess I should also be ashamed I am not running a desktop with pfSense as a router as well?
  • dave_the_nerd - Monday, November 14, 2016 - link

    Aside from the pfsense / FreeNAS issue - if you're using old desktop hardware as a server, yes, you should be ashamed. :-P

    If you are using a prebuilt distro like FreeNAS instead of rolling your own distro, you should also be ashamed. Or something.
  • MrCrispy - Monday, November 14, 2016 - link

    ZFS is expensive and hard. Can't mix and match drives, RAM hog, to expand a vdev you need to upgrade all disks, needs ECC ram, keeps all disks spinning, will slow down as you near capacity.

    The ZFS hype needs to stop. Its not at all suitable for a home user NAS, its meant for data centers.
  • bsd228 - Tuesday, November 15, 2016 - link

    some of us don't see a difference, Crispy. I value my data as much as my datacenters' data.
  • doggface - Tuesday, November 15, 2016 - link

    Pfft. RAID is dead. Any decent array these days, is likely to get data corruption from hw raid.

    ZFS is rock solid. Also, if for some reason your OS/COTS solution dies your data is at significant risk of death. ZFS datasets are kept locally and you can rebuild the dataset regardless of the hardware.
  • eldakka - Wednesday, November 16, 2016 - link

    RAID is dead? Huh?
    Sure, you can use ZFS without RAID, but that doesn't give you any hardware failure data protection.

    I've rarely seen someone not use ZFS in some sort of RAID arrangement:

    Software RAID (ZFS RAIDZ, RAIDZ2 and others) is still RAID.
  • doggface - Wednesday, November 16, 2016 - link

    Ok. You got me, yes, it is uses an array of disks. Let me be more specific, RAID5 is a risk not worth taking. The reason they call it RAIDZ and RAIDZ2 is because they are significantly different to normal raid 5/6. Any RAID5 array that is over 12tb total size (not pool size) is at a very high risk of corruption as soon as a disk dies, its not conjecture - it is math. ZFS mitigates the risks inherent in a system designed decades ago, and is a far superior option for massive and small deployments.
  • eldakka - Friday, November 25, 2016 - link

    OK, then let me be more clear.

    RAID = Redundant Array of Inexpensive Disks.

    ANY technology that uses multiple disks and incorporates some level of redundancy such that the ARRAY spread across MULTIPLE DISKS that can withstand the failure of 1 or more of those disks (you know, REDUNDANCY) IS a RAID array. Whether it's in software or hardware, whether they are fixed size stripes or variable sized (ZFS uses variable stripe sizes so it can optimize the size of the striping to each individual file) stripes, whether it uses stripes or separate ECC disks or complete mirrors, it is ALL a subset of the RAID paradigm.

    ZFS RAIDz, 2z etc are RAID arrays. Their implementation of adaptive striping sizes per file is a significant enhancement over standard RAID5 and 6 and so on, but it is just that, an enhancement of, or more sophisticated implementation of, RAID.

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