The lowly state of the art for file system checking and repair does not match what is needed to keep important data available for users. Current file system checkers, such as e2fsck, are complex pieces of imperfect code written in low-level languages. The authors introduce SQCK, a file system checker based on a declarative query language; declarative queries are a natural match for the cross-checking that must be performed across the many structures of a file system image.