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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  • tuxRoller - Friday, November 18, 2016 - link

    Raid is dead. The big data center distributed filesystems have moved to erasure coding (pick your parity! Who says 3 is all you need?).
    In fact, I'd say zfs is sitting at a rather odd intersection of: not best used for your desktop and not the best option for data centers. Surely there's some market there but it's still a bit of an odd duck.
  • tuxRoller - Thursday, November 17, 2016 - link

    How is it expensive? Freenas is free.
    You don't need a ton of ram unless you are deduping (they don't seem to offer an out of band dedup, like btrfs, so they have to keep a hash table of all the blocks along with their locations, hence the origin of the rule of thumb "1GB/1TB").
    It is, however, a ram hog (on Linux) in a slightly different way: whatever memory pages it claims, it owns and can't be reclaimed via the normal kernel methods (well, short of removing the module) unless it is on one of the solaris clones (it may not happen on the bsds as well, but I haven't really looked into the problem from their side).
    It doesn't NEED ECC much more than your laptop does (btw, your laptop actually does need ECC since that greatly improves system stability). That whole thing has been a bit misrepresented and is more about reducing your chances of false negatives (corruption) when deduping or compressing.
    I would, however, agree that it's overkill for your home server since it's quite complicated, needs tuning, and has a number of limitations you really need to be aware of.
    If you're going to roll your own I'd go with something like flexraid or snapraid (with my preference being snapraid due to it being extremely well developed, open source, great community and responsive developers---ganesh doesn't much like it because it's not a "live" raid (meaning it only backs up when you tell it to, hence, snapraid) but that's all most home users need---periodic backups), but the benefits are terrific: it hashes your data (and can scrub it so that silent corruption doesn't occur), you can add disks to the pool as you need them without a massive rebuild (in fact, it should just take up the disk and add it to the pool without much else, assuming the disk is empty), use it on whatever os (and with whatever fs) you want, supports parity levels that make zfs drool (up to 6, iirc), and, if something happens that causes one of your disks to become unrecoverable, the only data you lose is what was on that disk (no striping---this also means you don't get the faster read/writes that striping can offer but, unless you are using better than gigabit Ethernet you can't even make use of that speed).
  • jbrizz - Monday, November 14, 2016 - link

    You'd be better off comparing this stuff to OpenMediaVault. It's essentially a NAS stack that runs on top of Debian (you can get it as an installable distro or install it from Debian with apt). Pretty sure it does everything these commercial NAS OSes do and probably more. I'm running it on a little i3 6100 system at home it looks after all my home serving needs (torrents, plex, samba, openvpn, IP cam footage, virtualisation, crashplan cloud backup, webserver, mumble server, FTP server). 45w idle with 6 disks (spun up) and two SSDs in it.
  • jlabelle2 - Tuesday, November 15, 2016 - link

    I have an honest question to those promoting those FreeNas / DIY server. I am myself a DIY loudspeaker builder so I clearly know that what you pay for is not purely components but also all the development work behind.
    So a question to you (pwr4wrd, jbrizz, cdillon....), let's assume you are a normal person without good IT knowledge:
    * how long do you need to setup the NAS with a few users, folder access rights and services running compared to a Synology (for instance because this is what I have) that would require just a few minutes?
    * do you have mobile phone or tablet application to access in a friendly way your photos? Your videos? manage and launch downloads? control your camera? manage your emails on your server? manage your files remotely? share easily to friends files, photo albums with fine granular control?
    * do those systems support backup of cloud data to have incremental backup and recovery capabilities of your data in OneDrive, Google Drive, Box, DropBox...?
    * do those system can encode videos on the fly to decrease the bandwith necessary to have access to your video from remote places on your smartphones?
    * can you easily make cross-NAS incremental backup as my brother and father are also using a Synology NAS and we are making our off site backup in each other NAS?
    * does those OSs can act as iTunes server and TimeMachine destination?

    Those are just a few examples of very simple, out of the box capabilities on the Synology and I would be genuinely interested to know how easy ALL those non exhaustive features work on FreeNAS or other solutions you are proposing...
  • maximumGPU - Tuesday, November 15, 2016 - link

    good question, i would be interested in that as well. Maybe we can settle this issue that keeps cropping up on every NAS article. Honest answers appreciated.
  • jbrizz - Tuesday, November 15, 2016 - link

    If you can install Windows can you can install something like FreeNAS or OMV, so many people could use it (although not a "normal" person), but your need at the very least a willingness to tinker. I've never used FreeNAS, but OMV uses a plugin system from the WebUI to add extra things like Plex, webserver, OpenVPN server etc. which in theory should be easy to get working, but in practise it's far from it. For the average person who needs network storage, a prebuilt NAS is definitely the way to go.
  • darwinosx - Monday, April 3, 2017 - link

    The problem with a lot of the replies like yours is you are assuming NAS is just for network storage for most people when they do much more and are far easier to configure and run than roll your own.
  • jbrizz - Tuesday, November 15, 2016 - link

    And to better answer your questions, regarding OpenMediaVault:
    *a few minutes
    *a combination of OpenVPN and other apps would allow this, e.g. I use Remote Transmission GUI to start/monitor torrents so they are ready when I get home. My HikVision IP cameras have their own app which can be used when my phone is connected to my VPN.
    *Crashplan have a linux app which can be run headless without a graphical interface. This works well to backup 1.4TB of data for me.
    *Plex does this and miniDLNA (a DLNA plugin) can be configured to do this also. My i3 6100 has plenty of power to transcode 1080p on the fly.
    *Some disk arrangements support snapshots, although I don't use it so can't comment. Crashplan does incremental backups to the cloud which is (1 min, 15 min, 1 hour, 1 day etc, so very regular) works well for me. I have a gigabit fibre Internet connection to help support this.
    *I believe it does support TimeMachine and AFP with a plugin, not sure about iTunes or Apple TV.
  • jlabelle2 - Wednesday, November 16, 2016 - link

    Thanks for the honest question. It seems very cumbersome and with a mix of various inelegant solutions and I am still puzzled about people laughing at customer of those NAS system which are plug and play.
    Coming back to the few points I mentioned:
    * mobile app: is Remote Transmission an application existing on mobile phone? You spoke of Plex which is supposed to be great but was always much slower than Synology app for video and photo browsing. And Plex only stream MP3 music files even if I have FLAC. What about file management?
    * Cloud: a non graphical interface to setup backup with complicated file structure is really far from user friendly. What about support of cloud that people are using? Crashplan is for backup. I have Windows devices so I am using OneDrive like hundred of millions of users. Most used cloud storage are OneDrive, DropBox and GoogleDrive. What about this support on OpenMediaVault?
    * transcoding: good. Plex does a lot of thing but still not on par with proprietary solutions (see above).
    * Snapshots is not the same as "standard" backup. Again, I am not speaking of "backup" in proprietary cloud backup but cross-NAS. Crashplan needs to be paid, constantly, until the end of your life. When you have already a NAS, I do not see the need for that when I can do it freely across different NAS from my family. From your answer, I deduct that it is a no. Speaking of backup in the cloud, I have a cable connection with 25Mbps in upload which is more than 99% of the population. So it means on an average around 2.5Mo/s so for my 4To of backup, it is a 20 days upload backup!!! With a NAS, you can send the data with a HDD and just start the backup with the incremental part with the initial transfer of bulk data made physically. How do I do that with cloud services?
    * no support of iTunes or AppleTV is just a deal breaker for Apple users. Simply as that.

    All in all, it confirms that it is 1/ much more complicated and 2/ much less capable. sure, it may be cheaper for the one that can configure and manage it and are fine with the limitations. But it is far from being an universal solution.
  • eldakka - Friday, November 25, 2016 - link

    Not answering all the questions (I don't, for example, use cloud solutions for data backup or access - that's why I have NASes), so I don't use the cloud.

    However with respect to table/phone apps and Transmission. Transmission is a bittorrent client. The client can run in a headless mode ideal for servers (e.g. NASes). You can also get applications that run on your local computer and on Android devices, whether tablet, phone, media-players or 'computer'.

    But in the bigger picture, the 'app' for tablets and phones for Transmission and most of the other services you mentioned (photos, videos etc) is called "a browser". Most of these services (including transmission) offer, in addition to purpose-built apps, web browser enabled interfaces.

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