Linux Desktops
From Solaris to Linux
When the UVa astronomy department hired me, the main project they wanted me to design and implement was a way to transition their legacy Sun Solaris network over to cheaper Linux based PCs. Many of the astronomy related programs had already been ported from one platform and architecture to the other, and so the ability to change platforms was ready.
History
Originally, the design goals for introducing Linux PCs into our department was to create a 2nd parallel network completely separate from the Solaris machines. At the time, it was generally believed that Solaris was more stable and secure, and there was concern amongst the faculty that Linux would compromise those features. Initially a network based Linux home directory server was set up in tandem with the existing Solaris servers. Later, after about 33% of the users had transitioned to Linux, it was decided that the two networks should be re-merged together into one transparent platform that hosted both architectures of clients.
Servers
This migration of desktops spun off multiple sub-projects, such as migrating our single Solaris server (which was burdened with mail, web and NIS duties plus general processing) to separate, independent Linux servers.
- Our mail services were migrated over to a Postfix based system with the latest spam fighting techniques applied.
- Our web services were moved to a newer, higher capacity apache system.
- The Linux home directory server was designed as a redundant fail-safe cluster, since it is the most critical part of our network. This server was based on the heartbeat project that is included in recent versions of Fedora Linux.
- Finally, the last (yet very critical!) service was developing and deploying a backup service for our data.
Ultimately, the NFS home directory "cluster" was downgraded to a single host system (heartbeat proved to be unreliable during fail-over situations).
The NIS user password table was eventually migrated to an OpenLDAP database and expanded to include user data for other services, such as Samba (Windows logins), VPN, and user addressbooks. This massive LDAP project also allows for centralized Mac logins, additional website features and other exciting technologies.
Workstations and HPC Clusters
Our Linux workstation network is currently based on the CentOS project, which is an open source "rebuild" of Redhat's Enterprise products. Our HPC Clusters (hyades and pleione) are based on the Rocks Linux cluster distribution. Originally I used Fedora (Core 2, Core 4, Core 5, Fedora 7 and finally Fedora 9) before surrendering to the longer-term stability of CentOS.
What I Learned
This method of developing the Linux migration offered some unique advantages and disadvantages. On a plus side, the initial development of a parallel network allowed me to take more time than usual to really work with the desktop client image and make it every bit as useful and secure as what it was replacing, and even more user friendly. The initial adopters of Linux had a larger learning curve to transition from Solaris to Linux, but given the feedback from those people I've been able to make the transitions that follow almost seamless. The down side to transitioning this way is the process has taken far longer than most people expected (some holdouts still refuse to surrender their 10+ year old Sun workstations!).
Last Modified Thursday, July 9, 2009.