QUOTA.SYS, or the quota file, is a system file that resides in the master file directory of a volume and is used by the file system to keep track of the disk usage of each UIC on a volume. If you enable disk quota checking for a volume, the records of the file QUOTA.SYS contain all the UICs on the volume. The system constantly updates QUOTA.SYS to reflect the current disk usage, the maximum allowed disk usage, and the permitted overdraft for each UIC.
During the course of its operations, ANALYZE/DISK_STRUCTURE creates a version of QUOTA.SYS in memory that reflects the actual disk usage for each UIC. This version is eventually compared to the disk version of QUOTA.SYS. If ANALYZE/DISK_STRUCTURE detects any disparities in disk usage, ANALYZE/DISK_STRUCTURE notifies you. If you invoked ANALYZE/DISK_STRUCTURE with the /REPAIR qualifier, the disk version of QUOTA.SYS is updated.