It pains me to write this.
Has anybody ever done backups for Apache Lucene? (In particular, Solr, though I've no reason to believe that means anthing special for backup/recovery.) What did you do to do that, in broad strokes?
Note that I'm interested in responses in accordance with
jwz's rules here. I do not want to know what you think might work after you google those terms. I am interested in what you already did iff (no spelling error there) you have created backups of a lucene database (index, whatever you want to call it) that were usefully recoverable.
If you don't have a real answer, please, just say nothing.