“Speaking of on-disk B-Trees, ReiserFS’ biggest problems are all based on its use of flexible B-Trees,” suggested a reader on the DragonFlyBSD Kernel mailing list, pointing to the difficulty of detecting a failed node and then of rebuilding the B-Tree. HAMMER filesystem designer and author, Matt Dillon, explained, “if a cluster needs to be recovered, HAMMER will simply throw away the B-Tree and regenerate it from scratch using the cluster’s record list. This way all B-Tree I/O operations can…