The clusters had a shared OS image - that is a single, shared root filesystem for all members. To allow node-specific config files, there was a type of symbolic link called a “Context Dependent Symbolic Link” (CDSL). They were just like a normal symlink, but had a `{memb}` component in the target, which was resolved at runtime to the member ID of the current system. These would be used to resolve to a path under `/cluster/members/{memb}`, so each host could have its own version of a config file.
The single shared root filesystem made upgrades and patching of the OS extra fun. There was a multi-phase process where both old and new copies of files were present and hosts were rebooted one at a time, switching from the old to the new OS.