SolrCloud: read only node

[Uwe Reh]

Hi,

as service provider for libraries we run a small cloud (1 collection, 1 
shard, 3 replicas).  To improve the local reliability we want to offer 
the possibility to set up own local replicas.
As fas as I know, this can be easily done just by adding a new node to 
the cloud. But the external node shouldn't be able to do any changes on 
the index.

Is there a cheap way to restrict a node of a SolrCloud into a read only 
modus?
Is it a better idea, to do legacy replication from one node (master) to 
an external slave?


Uwe