Hi, In general, a high-availability system should have the following software services http://electronicdesign.com/boards/high-availability-rtoss-deliver-five-nine s-reliability : - Heartbeat support for each server and each application. - Event management capability for change notification. - Alarm management for error handling. - Transactions capability for check-pointing and rollback/restart. - Clustering for server management and applications links. - Reliable storage support for RAIDs and for journaling file systems. I want to develop a high-availability system on seL4, can anyone give me some suggestions? QNX has high availability support http://www.qnx.com/developers/docs/6.3.0SP3/neutrino/sys_arch/ham.html , can we learn something from them? Xilong Pei Tongji University 2015/6/11