Indicates how readily a stack member can take over as master
if the current stack master were to fail. Possible values are:
init (1) - the stack member is completing startup initialization.
syncing (2) - the stack member is synchronizing state information
with the stack master following startup.
ready (3) - the stack member is fully synchronized with the current
master and is ready to take over immediately.
syncError (4) - state information on the stack member is not correctly
synchronized with the current stack master.
For a stack member to take over as stack master with the least possible
network disruption, it must have the 'ready (3)' status.