$SPLUNK_HOME/var/run/searchpeers stores bundles from your search heads used by the indexer to run searches for them with the appropriate configurations. Indexing happens elsewhere, by default in
$SPLUNK_HOME/var/lib/splunk - see if that's fairly small compared to what you've defined on your second drive to confirm that the index path setting is working.
As for your searchpeers folder using 13GB, this can have several reasons:
- is your bundle huge, e.g. massive lookup files?
- do you have many search heads, each distributing different bundles? Consider merging the search heads into a search head cluster, reducing the number of different bundles on your indexers.
- are there old bundles from legacy search heads? These can be deleted.