Leigh Dyer looks at Sun’s attempts to keep Solaris relevant in a Linux world.
Just a few months ago the once-mighty Silicon Graphics Incorporated (SGI), champion of the computer graphics world, announced the end of the line for their IRIX operating system and MIPS architecture. SGI has moved to using Linux and Itanium, and it’s certainly not the first story along those lines: HP have moved their HP-UX OS to Itanium, though they prefer to push Linux these days, and while IBM continues to develop their POWER architecture, they too are pushing customers toward Linux instead of their own AIX.
It seems the only old school Unix vendor still pushing their own OS is Sun, with Solaris, an OS that has gone through some major changes in the last few years. Has it done enough to keep Solaris relevant in today’s market, and why does Sun insist on competing with Linux when other vendors have embraced it?
The latest release, Solaris 10, introduces a number of new features. It also revives one that had disappeared for a while: an x86 port, allowing Solaris to run on commodity systems. A key new feature is DTrace, a sophisticated dynamic tracing framework that’s designed to analyse the performance and activity of applications. What makes DTrace most interesting is that it’s designed to run with little or no performance impact, making it usable on production systems.
The most recent update of Solaris adds ZFS, a file system that challenges a number of long-standing ideas about storage. Traditional file systems don’t really care where they’re stored – the storage subsystem is just a black box that bytes can be written to and read from. ZFS integrates features similar to the Linux LVM layer, building file systems on top of storage pools called ‘zpools’, which are in turn built upon virtual storage devices. Those storage devices can be physical drives, or software RAID sets.
Part of the RAID functionality is a new RAID level called RAID-Z. It’s fundamentally similar to RAID-5, but it can vary the low-level RAID configuration as needed to maintain optimum performance. Keeping track
of these changes would be a nightmare in a hardware-based RAID system, but having it software and integrated into the file system means that information on the RAID setup can be stored in the file system itself, alongside other file system metadata.
If you’re wondering how ZFS would best be used in the field, the best answer is to look at the Sun Fire X4500. Sun calls it a ‘hybrid’ server that combines computing with storage, with two dual-core Opteron CPUs and an incredible 48 SATA hard drives in a 4U rackmount case. With 500GB drives that’s an insane 24TB of theoretical storage, though the real number would be lower once you implement RAID and add file system overheads.
You wouldn’t configure an X4500 in the same way as a traditional RAID array though: the idea is that you throw all the drives into zpools and then allocate storage from them as needed. You don’t want to have all the drives active at once, because ZFS can automatically map out dead drives and configure spares to replace them. The end result may be 12TB of usable storage, but it should be insanely fast and very solid, with maintenance to replace dead drives required perhaps once a year at most.
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| Sun's X4500 hybrid server seems custom-built for ZFS in Solaris 10. |
The OpenSolaris push
You can download Solaris 10 for free, but Sun knows of course that a proprietary, binary-only OS wouldn’t sit well with users used to the open source nature of Linux. Early in 2004 they began work on OpenSolaris, an open code base that today includes most of the code included in Solaris, including DTrace and ZFS. They’ve put a lot into the project, and it’s clear that they expect a lot out, with an emphasis on trying to create a community of open source developers around the project, much as Linux and other open source operating systems have. Future Solaris releases will be derived from the OpenSolaris codebase, in much the same way that StarOffice is built from the OpenOffice.org codebase.
Sun has no official OpenSolaris release that’s in a ready-to-install form, and they may not make one, besides the eventual release of an OpenSolaris-derived Solaris of course. A number of distributions have appeared that use OpenSolaris as a base for a complete OS though, with the most popular probably being BeleniX. It’s a live CD, and along with the OpenSolaris foundations it ships a full GUI, using the relatively lightweight Xfce desktop, and a selection of applications including Firefox and Thunderbird. It also has a basic hard disk installer, should you choose to run it on a more permanent basis.
Another interesting distribution is Nexenta, which is especially appealing to me as a long-time Linux user. It uses the OpenSolaris core, but places a Linux-style GNU userspace over the top, creating a system that looks, feels, and runs like a Linux system, at least until you get to the low-level functionality.
Like Ubuntu, Nexenta is based on Debian, and the most recent version is actually based on packages from the 6.06 (Dapper) release of Ubuntu. The core packages are different of course, but most of the other packages in Ubuntu have been rebuilt with little or no modification. After running through the single install CD you end up at a GUI login screen, and logging in reveals a complete GNOME desktop, with OpenOffice and friends all pre-installed.
Once you dig a little deeper than the GUI, the uncanny resemblance to an Ubuntu install starts to break down a little. Most of the command line tools are the same GNU versions that you’d find on Ubuntu, but the more kernel-specific tools, including process management tools like ‘top’ and ‘ps’, are OpenSolaris versions which differ significantly from the versions I’m used to. Annoyingly, Nexenta doesn’t ship with manpages for these tools, so you’ll have to go digging around online to find how to use them.
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| The BeleniX OpenSolaris live CD, running the XFCE GUI. |