Employ the use of a slow hard disk (local or network attached) for persistent storage and a fast SSD (preferably local) for caching. This combination can be used as data directory for Apache Solr.
In this example, we have a hard disk at /dev/sdb and the SSD at /dev/nvme0n1. The entire hard disk (/dev/sdb) can be used for persistent storage, but in this example we are using just a single partition (/dev/sdb1) as the persistent store.