The solr weakness fault tolerance on ext4

In few days ago ours machine (with solr) was crashed.
We rebooted machine and solr, The solr looks like validly behavior.
But, The solr is not valid because following :

• Exists Solr core.
• Exists /tmp/solr directory and /tmp/solr/data/solr_core directory.
• Exists /tmp/solr/solr.xml and exists solr/cores/core tag.
• We can start Solr Server without exception.
• "$ curl http://localhost:8983/solr/solr_core/select?" returns 404 Not Found.

And I found the file of '/tmp/solr/data/solr_core/index/segments.gen' is empty file.
So, I think there is no (or weak) fault tolerance about Solr.

I hope the solr grow up crash-free server.
For example, File handling is atomically as much as possible.