Some operating systems need no introduction. Windows, Linux, macOS. Then there is Solaris: the system that ran entire banks, telcos and data centres, and that today survives in a handful of very specific niches. If you have ever heard the name and quietly filed it under «some car brand», you are in good company.
Start with this. Solaris matters today mostly for what it anticipated. A filesystem that takes snapshots, containers, a fine-grained look inside a running machine: all three were popularised in Solaris before most people had even heard the words. Study Solaris and you are studying where half of modern Unix comes from.
The short answer, for anyone in a hurry: Solaris is a Unix operating system created by Sun Microsystems in 1992 and owned by Oracle today. It still runs, propped up by its installed base, and it will keep running for a while. What follows is why, what it gave the rest of us and how it stacks up against Linux.
What is Solaris?
Solaris is a Unix-type operating system created by Sun Microsystems in 1992 and maintained by Oracle since 2010. Sun built it for high-end machines: powerful servers, many processors, and environments where reliability is not up for debate. It runs on SPARC processors, the ones Sun designed itself, and on x86-64.
Technically the label reaches further than «operating system». Solaris is an operating environment, and that bundle includes the kernel, the command interpreter and a pile of tools and libraries on top. It is why older documentation calls it the «Solaris operating environment» rather than a plain operating system. The version alive today is Oracle Solaris 11.4, released in 2018 and still receiving periodic updates.
Fix one distinction early, because it saves arguments later. Solaris is not a Linux distribution. It shares the Unix surname and a set of tools, but the kernel, the package manager and the licence are all different. When someone says «Unix» and means «Linux», Solaris is the counterexample that proves the two are not the same thing.
Wind the clock back to the nineties and none of this was academic. If your company needed a database that could not go down, or a room of servers swallowing millions of transactions a day, Solaris was one of the few answers on the table. It arrived as a package: the machine, the operating system and the support contract, all from the same vendor, all on the same invoice.
Its history: from SunOS to Oracle
- 1983: SunOS. Sun’s first system. It was built on BSD Unix, the line developed at the University of California, Berkeley.
- 1992: Solaris is born. Sun rebrands its system and adopts the UNIX System V base, specifically SVR4, the release AT&T and Sun had merged with BSD. The story of Solaris proper begins there, even if it was still SunOS 5.x underneath.
- 1998: The «2» is dropped. After Solaris 2.6, Sun retired the prefix and the next release shipped straight as Solaris 7. A marketing detail that still trips up anyone reading through old version numbers today.
- 2005: Solaris 10 and OpenSolaris. Sun releases the source code under the CDDL licence and the OpenSolaris project is born, with the aim of getting closer to the free-software community and taking on Linux.
- 2010: Oracle buys Sun. The deal closes in January. Oracle walks away with Solaris and Java, sets OpenSolaris aside to focus on Solaris 11, and the code is closed again.
- 2010 onwards: Illumos. The community does not give up. Garrett D’Amore announces a free fork of the open OpenSolaris code in mid-2010. Out of that come illumos and distributions such as OpenIndiana, OmniOS or Tribblix, all still alive today.
Behind Sun stood names with a story: Andreas von Bechtolsheim, who walked away from his PhD to found the company. Bill Joy, who wrote much of Berkeley Unix, including editors and shells you may still use, and ended up as chief scientist. Vinod Khosla and Scott McNealy. These were people who, in the 1980s, built Unix workstations when almost nobody was buying them.
The four ideas Solaris handed to modern Unix
If Solaris is still studied, this is the reason. Four technologies it launched first and that you now find, under other names, in almost every modern system. Take them one at a time: what each one was and why it mattered.
ZFS: the filesystem that changed everything
ZFS is a filesystem and volume manager that Sun started building in the early 2000s, announced in 2004 and shipped to customers in the 6/06 update to Solaris 10. Jeff Bonwick led the team, and the name came from zettabyte: it aimed at storage scales that sounded like science fiction back then.
Size was only part of the story. ZFS checks data and metadata with end-to-end checksums, so it detects and corrects silent errors that other systems swallow without ever noticing. Snapshots and clones cost almost nothing, because nothing is copied until it is needed. And volumes and filesystems are managed as one thing, a pool. Much of that now reaches Linux, FreeBSD and macOS through OpenZFS, but it started here.
There is a detail underneath that explains why the snapshots are so cheap. ZFS never overwrites live data in place. It writes new blocks somewhere else and flips a pointer, so the old blocks stay exactly as they were until the system decides to reclaim them. That single design choice is what lets you take a consistent point-in-time copy of a filesystem in the time it takes to type the command, however much data sits behind it.
Zones: containers before the word existed
Zones arrived with Solaris 10. They are isolated environments inside one system: each has its own processes, its own network and its own filesystem, and from the inside you cannot see the rest, not even with root credentials. They were first called Solaris Containers, and they let a single big machine host what previously demanded one machine per application. With branded zones you could even run an older Solaris release or Linux binaries. By the time Docker made containers popular, the idea had already been running in production for almost a decade.
Think about what that saved. One well-sized machine could replace a rack of half-empty servers, each one running its own copy of the operating system, each one needing its own patch schedule. The isolation was the whole point, and it was sitting there in production years before the rest of the industry started talking about containers as if they were new.
SMF: services that pick themselves up
SMF (Service Management Facility) is the service management system that Solaris 10 introduced. Each service declares its dependencies and its restart policy. If one falls over, SMF brings it back and leaves it in the state it belongs in. Administrators drive it with svcs and svcadm, and it replaced the sprawl of startup scripts scattered around /etc/rc. It sounds familiar because systemd did something similar on Linux years later, with a good deal more controversy attached.
DTrace: looking inside the system without slowing it down
DTrace is a dynamic tracing tool that also arrived with Solaris 10, written by Bryan Cantrill, Mike Shapiro and Adam Leventhal. It lets you ask what the system is doing, which process, which function, how long it takes, while the machine is running and without stopping the service. When it is not in use it costs nothing: there is no instrumentation sitting around waiting to consume resources. That made it possible to diagnose problems in production that once forced you to reproduce them in a lab. It now exists on illumos, FreeBSD and macOS. The Linux world took years to get something equivalent.
Two more pieces sit alongside those four. IPS (Image Packaging System) and boot environments both arrived with Solaris 11 in 2011. Updates are applied to a copy of the system held on ZFS, and if something goes wrong you boot the previous version without touching the disk by hand. One curiosity on the side: Solaris 2.5.1 was the only version ever to support the PowerPC architecture, and it was cancelled shortly after release.
Solaris vs Linux
The real split was never about commands. It was about who paid for the machine. One system was sold together with the hardware, the other could be installed anywhere without a licence fee. In practice that shakes out across five fronts.
| Solaris | Linux | |
|---|---|---|
| Origin | Sun Microsystems (1992) | Linus Torvalds (1991) |
| Licence | Proprietary (with an open past) | Free (GPL) |
| Hardware | Historically SPARC, also x86 | Practically everything |
| Strong at | Large systems, reliability, ZFS | Flexibility, community, cloud |
| Today | Niche (banking, telco, legacy systems) | Dominant on servers |
Brought down to the day to day, three differences stand out. Package management: Solaris uses IPS with pkg, while Linux divides the work between dpkg, rpm and their many derivatives. Support: with Solaris the people who use it pay for it and a vendor provides it, while with Linux it depends on the distribution and plenty of them are free. And hardware: Solaris was born attached to SPARC and today is limited to modern SPARC and x86-64, while Linux runs on almost anything with a chip in it.
Culture explains all of the above. Solaris was born to sell expensive hardware with matching software, and Linux was born to be installed anywhere without paying for a licence. Once hardware got cheap and Linux matured, the scales tipped and they never tipped back. The strange part is that the exchange ran both ways. Solaris’s ideas ended up inside the Linux ecosystem, and in a real data centre it is completely normal to find Solaris servers sitting next to switches and subnets that speak TCP/IP like any other machine.
Where is Solaris still used?
In very specific niches, yes, and for a deeply unromantic reason: replacing it costs more than keeping it. There are critical systems in banking, telecommunications and government that have been running on Solaris for decades, and where a botched migration gets paid for in outages. So the system stays put, quietly serving the people who cannot afford that risk.
The maths behind that decision is brutal and simple. A migration touches the database, the storage, the backup software, the monitoring and the people who know how the thing behaves at three in the morning. Add the testing, the rollback plan and the years of tuning nobody documented, and the invoice gets long before anyone writes a single line of code. When that bill lands on the table, most teams decide the old system can live another few years.
In telephony and voice over IP, its reliability was the perfect excuse not to move. In banking, Solaris was for years the natural platform for Oracle Database: large relational databases with ZFS underneath. When fine-grained diagnosis shows up on those networks, latency, packet loss, jitter, the system suffering it is usually an old acquaintance.
Oracle is not alone in this, either. The free illumos code lives on in distributions such as OpenIndiana, OmniOS or SmartOS, and some storage vendors use it as the base for their filesystems. Oracle, for its part, keeps Oracle Solaris 11.4 on a schedule of periodic updates and has repeatedly pushed back the end of extended support for Solaris 10 and 11.3. That is a sign there is still installed infrastructure somebody considers critical.
For almost everything else, Linux and modern Unix-like systems have taken its place. Still, it pays to remember that a lot of what feels new to us now arrived first on a system most people have never touched.
Frequently asked questions
What is Solaris and who created it?
A Unix-type operating system created by Sun Microsystems in 1992. Since 2010 it belongs to Oracle, which acquired it when it bought Sun.
Is Solaris free software?
No. It is proprietary software today. Between 2005 and 2010 Sun released its code under the CDDL licence with the OpenSolaris project, but Oracle closed it when it bought the company. The free fork of that code is illumos.
How is Solaris different from Linux?
In licence, original hardware and philosophy. Solaris was the system for large Unix machines sold with their hardware, while Linux is free and runs on almost anything. Ideas such as ZFS, zones or DTrace were born in Solaris and ended up influencing Linux.
Does Solaris still exist?
Yes. Oracle maintains Oracle Solaris 11.4 with periodic updates and still supports earlier versions for customers who need them, above all in banking, telecommunications and large legacy systems.
How are Solaris and illumos related?
illumos is the free fork of the OpenSolaris code, created in 2010 after Oracle bought Sun. Strictly speaking it is a separate project, and it shares much of its code and technology with Solaris (ZFS, DTrace, zones). Distributions such as OpenIndiana or OmniOS are built on illumos.
Was ZFS born in Solaris?
Yes. Sun developed ZFS for Solaris and it reached customers in 2006. When Oracle closed the code, the project continued in the community as OpenZFS, which is now the version running on Linux, FreeBSD and macOS.
The bottom line
Solaris is the story of a system that once ruled the data centre and lost the battle to something cheaper, more open and more flexible. It was a solid system that hit a bad moment and carried a bad licence, and that was enough.
Its legacy, though, is everywhere. ZFS, containers and system observability were all cooked up there first. If that timeline is your kind of thing, here is the history of operating systems, from the first mainframes to today.