NFS problems in failover – MC Service Guard. Applicable to other Linux HA clusters

Problem: Two Linux servers (RHEL4) running NFS Server in High-Availability (failover) mode. When failovering the resources, an NFS client can continue to work. When failing back, the NFS client times-out for 5+ minutes. Further problem information: While using RHEL3, that same (exact) configuration worked flawlessly. Solution: set NFS options to UDP instead of TCP. Explanation:…

Linux as a WAN router

I will discuss the issue of placing a Linux machine as a router, and some special cases where things might play a bit different. The most common scenario is of placing the Linux as some sort of PPP or DHCP-via-cables router. It might look like this: In this picture, the Linux machine actually recieves, via…