Sun Microsystems has sold its mainframe re-hosting business to Clerity Solutions for an undisclosed sum. 

Clerity is a software and services firm specialising in legacy transition.

Mainframe re-hosting allows customers to transfer applications originally written for expensive-to-maintain mainframe computers to commodity servers.

Sun originally acquired the re-hosting technologies in 2001 from Critical Path where they were used to migrate customers' applications from mainframes to generic Unix servers. 

But Sun decided that under its management the re-hosting business would support only Solaris, Sun's proprietary Unix variant.

Clerity will develop the technologies it has bought from Sun to support migration to open source Linux, AIX and HP-UX (IBM and HP versions of Unix respectively) as well as Solaris. 

"Customers will welcome this move because more often than not they are looking for vendor neutrality when undertaking migrations," said Peter Critchley, strategy director at consulting and technology integration group Morse. 

"There is currently a lot of interest from businesses in migrating mainframe applications to open systems to make them easier to manage and more cost effective.

"However, in reality, people are usually hesitant when it comes to migrating business-critical applications because they worry about the risks.

"Hence they need to ensure they manage the risks by developing solid migration plans that involve thorough testing and the ability to roll back systems if problems do occur."

Clerity has acquired Sun's Mainframe Transaction Processing and Mainframe Batch Manager software, in addition to its mainframe migration tools, associated services and 27 employees.

Sun claims to have done more than 1,200 re-hosting implementations for more than 80 customers worldwide.

Clerity estimates that there are another 100 or so prospective customers either using the Critical Path software on non-Sun platforms or are interested in doing so.

Sun has never recovered consistent profitability since the dotcom crash and is in the throws of extensive restructuring designed to save as much as $590m annually. The restructure is likely to result in up to 5,000 job losses.