Moving from SunRay to ThinLinc

by Tobi Oetiker

For years we have been using SunRay as our prime office work environment. Originally running on Solaris, then with Debian and for the last few years with Ubuntu. A really pleasant working environment. No fan noise in the offices, super simple session re-connect from all stations. Good performance.

There were also a few downsides:

no official support for Ubuntu Linux
only limited support for Video
no 3D acceleration
no support for 3.x Linux (ALSA Sound)

but we managed, and overall the system ran well enough.

With the Oracle transition though the problems grew. Traffic on the SunRay mailing list dwindled to a trickle. All requests for adding support for Ubuntu and newer kernels went unanswered. When we tried to get SunRay software running on Ubuntu 12.04 we found that not only the sound support did not work, also the directory service seemed to have issues. Earlier this year Oracle changed their licensing scheme again, so that we were not able to get firmware updates for our SunRay clients anymore (despite countless emails and phone conversations we were not able to solve the problem).

In other words, we were ripe for a new solution.

Cendio ThinLinc

Peter Astrand of rdesktop fame had mentioned ThinLinc at some point on the SunRay mailing list, so I had a closer look. ThinLinc comes in two parts, a server software package to be installed on a Linux server (they support both RedHat and Ubuntu), and a client package for accessing the server. The client is available for Linux, Windows and Mac.

One afternoon I downloaded a demo setup from the Cendio Site. It installed without much fuss and as I started the client on my laptop and opened a YouTube video, I was blown away. Smooth playback, full screen. Sold!

Remained the problem of replacing the SunRay desktop clients. I had recently bought the 3plus model, which is able to drive two 2560x1600 screens. Cendio does not recommend any particular thin clients as desktop devices for use with their system. They say that the only requirement is that the thing lets you install their client software. They even have packages prepared for the more popular thin clients available.

While searching for a suitable device, I was astonished to find that no one seems to be able to touch Oracle SunRay 3plus when it comes to hi-res screen support. Even when looking for only one 2560x1600 screen, there are not that many offers. I eventually settled on the HP t610 (H1Y29AT) which promised decent performance and good graphics capabilities.

The first tests with the HP t610 were disappointing. The super smooth performance I had seen on my laptop was not to be reproduced. It turns out, that the TigerVNC based ThinLinc system is quite CPU heavy on the client side as it is using JPEG compression for efficiently transferring some of the screen data. I got in touch with the Cendio folks, who investigated the problem and found that the assembler optimized code in libjpeg-turbo was running into serious performance trouble on the AMD CPU powering the HP device. Once the bug was fixed, performance shot up by a factor of about 10.

So when shopping for thin clients, you might want to keep in mind that screen update performance is also CPU bound. The latest AMD and Atom Clients should be doing pretty well though.

With all the testing successful, we decided to go ahead and make the switch.

There is more

We have since found that ...

sound works much better with ThinLinc than with SunRay. It is all based on pulse audio
we could get Skype to work
PXE booting the HP t610 devices disk-less with Ubuntu 12.04 from an NFS server gives us optimal control over the thin client environment (not as hands-off as with the firmware based SunRay, but good enough)
the ThinLinc client forwards local storage devices via a user-space NFS server to the ThinLinc server, making access to USB sticks and cd drives a breeze
having the ability to add our own code on the thin client opens up a host of quick win customizations, unthinkable with the SunRay system like supporting custom hardware attached to the thin client
we could do secure and fast remote sessions from home easily since all communication is ssh based. No need for VPN setups any more
a thin client environment can be built without writing and maintaining any kernel drivers.
switching ssh to Blowfish encryption in the ThinLinc client gives an additional performance boost as this leaves much more of the CPU power for the image decompression.

What we have not yet tested is the support for accelerated 3d graphics, Cendio also advertises as one of the ThinLinc features in connection with the VirtualGL project. Since our ThinLinc servers run on KVM, we first need to tackle the issue of making a graphics card accessible from within a KVM guest.

Since June 2012 we are happily working on ThinLinc. We like the system so much, that we decided to partner with cendio to be in an optimal position to support others in making the move.

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