You can check Infinispan user guide chapters 5 (Persistence) and 16 (Infinispan as a storage for Lucene indexes). Chapter numbers are from Infinispan 8.2. Hibernate search also provides a "default-hibernatesearch-infinispan.xml" file to start with. You basically need to add persistence to metadata and actual index caches. Here is the one I use for index cache:
<distributed-cache name="LuceneIndexesData" mode="SYNC" remote-timeout="25000">
<transaction mode="NONE"/>
<state-transfer enabled="true" timeout="480000" await-initial-transfer="true"/>
<indexing index="NONE"/>
<locking striping="false" acquire-timeout="10000" concurrency-level="500" write-skew="false"/>
<eviction max-entries="-1" strategy="NONE"/>
<expiration max-idle="-1"/>
<persistence passivation="false">
<jdbc:string-keyed-jdbc-store preload="true" fetch-state="true" read-only="false" purge="false">
<jdbc:data-source jndi-url="java:comp/env/jdbc/..."/>
<jdbc:string-keyed-table drop-on-exit="false" create-on-start="true" prefix="ISPN_STRING_TABLE">
<jdbc:id-column name="ID" type="VARCHAR(255)"/>
<jdbc:data-column name="DATA" type="MEDIUMBLOB"/>
<jdbc:timestamp-column name="TIMESTAMP" type="BIGINT"/>
</jdbc:string-keyed-table>
<property name="key2StringMapper">org.infinispan.lucene.LuceneKey2StringMapper</property>
<write-behind/>
</jdbc:string-keyed-jdbc-store>
</persistence>
</distributed-cache>
This example uses JDBC because it works on a dynamic cluster. You need to replace "jdbc:string-keyed=jdbc-store" with a "file-store" if you want to store the index a file.