TrueNAS CORE and SCALE - history
Starting with a brief historical sketch, for which I apologize, but a little here is necessary. In 2005, the FreeNAS project was launched as free open source software. It was developed in parallel with its Enterprice version until September 2020 when the developers at iXSystems got tired of maintaining two separate product lines. That's how a unified version of the software, still known as TrueNAS CORE, came out in November 2020.
For a variety of reasons to which I'll return shortly, TrueNAS CORE has limitations that made it significantly more difficult to develop it in the direction of clustering individual servers, into one large, redundant and scalable cluster. The next important, and very difficult, goal on TrueNAS CORE was to start supporting Docker-based containerization. This is how the TrueNAS SCALE branch was created, also as free open source software.
Let me just mention that the clustering option, for the moment, to say the least, is in question. That's because Red Hat, which develops the Gluster FS software on which castration is, or was, based, has quite unexpectedly announced it will no longer continue to either develop the software or even patch bugs. So for the moment, the functionality of full-scale castering, to put it simply, does not exist. I have heard from iX Systems engineers that they are looking for another solution. One proposed intermediate solution, although of limited use, is to use Syncthing software for background synchronization.
TrueNAS CORE and SCALE - what do they have in common?
Both TrueNAS CORE and SCALE systems are actually nicely packaged graphical interfaces for managing and sharing storage space with users. They work great as file resource servers whether as NFS, SMB or iSCSI. What is quintessential to both systems is ZFS which underneath manages the data on the disks for us. For those interested, why ZFS? I invite you to the material "TrueNAS - ZFS why is it awesome ?".
Both systems have a similar relatively comfortable interface for the user. Both are open source software, which means that firstly you can use them for free, and secondly, because of their popularity on the Web, you will most likely be able to find answers to potential questions or solutions to potential problems.
Behind both of them, too, is the same experienced team of developers creating software that is almost identical to that thrown into official devices. And these cans with the TrueNAS logo are also trusted by small medium and large companies in Poland. Some are really big and well-known brands. Unfortunately, I can't name names, because in general, for various reasons, they simply don't wish to do so.
TrueNAS CORE and SCALE - what makes them different?
So what is the difference between TrueNAS CORE and SCALE really? The main difference is the system on which they are built. TrueNAS CORE is based on FreeBSD. TrueNAS SCALE, on the other hand, is built on Debian which is one of the Linux distributions.
So what is the difference you will ask? Which is a great question. Rushing to answer the question I just asked myself, I answer: FreeBSD which, although proven stable and secure, has its limitations. FreeBSD, to say the least, is not the first choice when it comes to Docker, Kubernetes containerization, which is currently in a huge onslaught. Additional functionalities such as Nextcloud, Plex and many, many others in CORE are based on so-called Jails. Yes when you know them and automate them, they are good and robust solutions. It's just that in practice in new implementations they are very rarely used anymore. Applications implemented in Jail are difficult to transfer between different systems, not to mention transferring between different distributions. Besides, you can only fire at them what runs on an identical version of the kernel as the host system's kernel. All this makes the development of Jail technology basically dead.
Here, all in white enters Debian, which is one of the more popular Linux distributions. TrueNAS SCALE was just based on it. In Debian, there are no problems in Docker-based containerization. In SCALE, applications are just based on Docker. Both Debian itself and Docker-based containerization technology are being developed rapidly. This makes the applications in SCALE, unlike in CORE, develop a bit "by themselves". The number of deployable applications grows very rapidly, as they do not need to be adapted and maintained as Jail, but only need to use existing whole container images using Docker. In addition, the effort to update all applications in practice, unlike Jail, is flipped to the maintainers of the applications or the maintainers of the used Docker images themselves because whole containers are updated.
As a result of the difference in the development dynamics of FreeBSD and Debian, i.e. TrueNAS CORE and SCALE, another important difference arises. It is about the device driver. If some new model of network card, motherboard or whatever comes on the market, in practice it will be supported much faster before Debian than by FreeBSD. Often, because of the scale of use, it will be more refined. In cases of rarer versions of devices, FreeBSD may never get around to supporting such devices. Hence the "capriciousness" of TrueNAS CORE regarding, for example, network cards. For the uninitiated, if you're looking for network cards are CORE then let it be anything on an Intel chipset and you should be fine. Otherwise things can vary. Sometimes on some folding hardware is that there are problems with the driver and it's hard to tell what and how? After upgrading to SCALE often everything works as expected.
From a rather niche topic already on the table regarding TrueNAS CORE and storage in general, is multipath. It's a functionality available in SAS-class drives, which are more expensive, but also found in NearLine SAS drives, which are already not much more expensive on good NAS drives. It allows one drive to be connected via two redundant cables and even two different controllers. It can give us a really high level of redundancy. Although to be accurate there is multipath support in CORE, but it is no longer developed in the open source version. Unfortunately, full support for such high reliability that multipath already exists only in the Entrprise version to be bundled with the original TrueNAS boxes.
From the news in TrueNAS SCALE in March 2024 in an early test version "nightly" will land, completely rewritten deduplication functionality. You can download and test it. The new version called simply "fast dedup". It is said to be significantly more efficient in terms of resource efficiency, among other things. We'll see, check it out.
At the moment that is March 2024 in TrueNAS SCALE. there is a problem with elastic RAM adaptation for ARC cache. This is not a problem of TrueNAS itself but of the aforementioned Debian on which it is based. As a result, ARC cache occupies at most half of the RAM which can make the other half unused. Yes it can be modified manually but that's for another discussion .
There are also differences about performance between CORE and SCALE. It's also not that one is faster only it depends on the specific case. But first of all, the differences are not some big ones and secondly, this is also changing as SCALE progresses.
When to choose TrueNAS CORE?
So when to consider TrueNAS CORE? For the moment, it is a well-proven, solid piece of software. Admittedly, TrueNAS engineers assure that the project will be supported all the time. it looks like it won't land any more significant updates or features. There will probably be security patches or bug fixes coming out.
If you need a NAS to be a NAS. just keep data there in a reliable, tested way, enjoy the benefits of ZFS, redundancy, replication, performance optimization. If you don't need some fancy hardware, then TrueNAS CORE may be for you.
Besides, if you have an existing working CORE implementation and you don't need new functionality it's probably worth leaving since it works well.
When to choose SCALE?
TrueNAS SCALE has been with us for more than three years. In the beginning it had some different problems. These included problems with the graphical interface, which, although similar to CORE, was written from scratch. The data handling underneath, i.e. ZFS itself, works without major problems. I must admit that during this time something changed from one update to another, new features were added, it was clear how dynamically work on SCALE is going on. Now it seems much more mature.
So when to choose TrueNAS SCALE? If you plan to use for additional functionality in the form of applications, for example. At the moment there are already dozens of applications natively supported by TrueNAS. Even if your application is not there you can always install any docker image and fire it up. If you plan to use new enhancements, features like "fast dedup". Or others coming in the future. Also if you will have hardware compatibility issues. Yes there could be reasons to choose just SCALE
When to choose Truenas enterprise?
So what is the future of CORE or is it actually already dead? It looks like we will be pushed back over time to the SCALE version. This is not surprising, since it is problematic to maintain software in two versions. CORE, through its lack of new functionality, will become more and more outdated and will probably be pushed back over time.
As confirmation, it is also worth mentioning that the upgrade from CORE to SCALE is a matter of the proverbial "click". In the other direction it is no longer so easy.
However, at the moment it doesn't look like CORE is going to stop getting security updates, that's good news. So we can continue to use it quietly for the next few years.
The future of CORE
So what is the future of CORE or is it actually already dead? It looks like we will be pushed back over time to the SCALE version. No wonder because it is problematic to maintain software in two versions. CORE, through its lack of new functionality, will become more and more outdated and will probably be pushed back over time.
As confirmation, it is also worth mentioning that the upgrade from CORE to SCALE is a matter of the proverbial click. In the other direction it is no longer so easy.
However, at the moment it doesn't look like CORE is going to stop getting security updates, that's good news. So we can continue to use it quietly for the next few years.
Summary
So in a nutshell I tried to share with you a little of my own knowledge, a little of information from inside iX Systems and a little of conjecture to rearrange the current situation on the difference between TrueNAS CORE and SCALE. Well, and the future of CORE .