IT hosting company Rackspace is going after what they describe as the most notorious patent troll in America. The company filed a lawsuit against Parallel Iron and IP Nav, patent assertion entities (PAE) that make money by licensing patents to customers rather than crafting their own goods based on the patents they own.

The legal move comes after Parallel Iron sued Rackspace and 11 other companies last week. The firm claimed that the defendants infringed on three patents covering the use of the open-source Hadoop distributed file system (HDFS). Parallel Iron has sued at least 23 others over this same patent since June 2012 including Amazon, Facebook and Oracle, just to name a few.

Rackspace first ran into legal issues with IP Nav back in 2010 when they accused the hosting company of patent infringement but wouldn’t tell them what specifically it was about until Rackspace agreed to sign a forbearance agreement. This agreement said that either side would give the other a full 30 days notice before perusing any legal action. The hosting company said they signed the agreement but the patent troll broke the agreement and sued without giving prior warning.

The latest lawsuit was filed in the US District Court in San Antonio and cites breach of contract and a declaratory judgment saying Rackspace does not infringe on the three patents in question. For what it’s worth, Rackspace was recently granted a dismissal of a lawsuit by Uniloc that claimed they infringed on a patent related to processing floating-point numbers.