Any thoughts on what files are essential to restore in the event of a complete system crash?
I second Joe Atzberger analysis. Your backup policy must be adjusted on data update periodicity. A good practice is to document backup AND restore. You must know and test by advance what you will have to do in case a restore is required. You may need a partial or a complete restore depending of situation: complete disk failure or just DB data corruption. Don't forget that with Koha 3 indexes are built outside MySQL DB: in Zebra. You can't save Zebra indexes synchronically with MySQL DB. Hopefully, Zebra indexes can be rebuilt easily and almost quickly. You must know how to do it in a recover after crash scenario. Other systems are also possible involving disk partitioning and mirroring. -- Frédéric