HDP 2.5 $ACCUMULO_HOME

[#1]

Where is the environment variable $ACCUMULO_HOME defined for HDP 2.5.3? In the config I can only find references to this variable for further directories but not the actual definition.

In /usr/hdp/current/

There no longer is a single accumulo folder, rather I see several folders (accumulo-master, accumulo-gc, accumulo-tracer, ...)

[#2]

These are all linked to a single directory, so any of them would be fine. I typically use the client directories for HDP services, e.g. accumulo-client. The ACCUMULO_HOME variable is often not set explicitly and is determined by the accumulo scripts to be the parent directory of bin/accumulo.