In addition to the compute nodes there are also dedicated I/O nodes, login nodes and nodes set aside for serial compute jobs. The login nodes can be used for editing, compilation, profiling, de-bugging, job submission etc. When a user connects to HECToR via ssh the least loaded login node is selected to ensure that users are evenly loaded across the system and that no single login node ends up with an excessive load.
HECToR has 12 I/O nodes which are directly connected to the toroidal communications network described above. These I/O nodes are also connected to the data storage system (i.e. physical disks). The data storage on HECToR consists of 576 TB of high performance RAID disks. The service uses the Lustre distributed parallel file system to access these disks.