Part I discussed performance and and some data integrity features of ZFS. Now for some more cool features and the StorageMojo.com conclusion.
Physician, Heal Thyself
On-disk bit rot is a real and continuing problem. For a lot of reasons, data can go wrong. The important thing is getting it fixed. As mentioned in Pt I, ZFS separates checksums from their blocks, so it can detect both corrupted and/or incorrect blocks. It also fixes them when found in the course of an I/O.
Even better, ZFS maintains a background process that traverses the metadata and verifies the validity of each block. This process is analogous to the ECC memory scrubbing that EMC used in the original Symmetrix line with its large, single point of failure cache.
Whether fixing a single block or replacing a failed disk, ZFS uses the tree-based checksum structure to ensure valid data.
Snapshot Copy, Cheap. Real Cheap.