Solaris ZFS Administration Guide

File System Validation

In addition to file system repair, the fsck utility validates that the data on disk has no problems. Traditionally, this task is done by unmounting the file system and running the fsck utility, possibly taking the system to single-user mode in the process. This scenario results in downtime that is proportional to the size of the file system being checked. Instead of requiring an explicit utility to perform the necessary checking, ZFS provides a mechanism to perform routine checking of all inconsistencies. This functionality, known as scrubbing, is commonly used in memory and other systems as a method of detecting and preventing errors before they result in hardware or software failure.