Cloud services provider Rackspace has hit back at what its describes as one of the US’s “most notorious patent trolls”, a firm called Parallel Iron, saying its 500 percent rise in legal bills meant it had to take a more aggressive stance. 

Rackspace said last week it was named among 12 firms accused of infringing Parallel Iron’s Hadoop Distributed File System patents.

But Parallel Iron is little more than a patent troll that seeks to wrangle settlements out of firms to avoid protracted courtroom battles, said Alan Schoenbaum, general counsel for Rackspace.

“We aren’t going to take it,” he wrote on a company blog.

According to Schoenbaum, Rackspace had been embroiled in a previous patent suit with Parallel Iron in December 2010, which it said was known as IP Navigation Group at the time. At that time, the two firms reached a truce under which they agreed to give the other 30 days’ notice before bringing any subsequent suit.

“We have sued IP Nav and Parallel Iron in federal court in San Antonio, Texas, where our headquarters is located,” said Schoenbaum. 

“We are asking the court to award Rackspace damages for breach of contract, and to enter a declaratory judgement that Rackspace does not infringe Parallel Iron’s patents.”

Schoenbaum said Rackspace had seen its legal bills rise 500 percent since 2010 because of the increasing number of patent claims it’s forced to defend.

Last month, Rackspace won a significant case against Uniloc, over the patenting of mathematical algorithms.