Each filesystem has up to five types of quota limits that can be enforced on it. These limits are specified in disk blocks, usually 1,024 bytes each:
- Per-user hard limit
The hard limit is the maximum amount of space an individual user can have on the system. Once the user reaches his quota limit, he won’t be allowed to write files to the disk.
- Per-user soft limit
Each user is free to store data on the filesystem until reaching her soft limit. The soft limit implements a sort of warning zone, instructing the user to clean up while still allowing her to work. When the amount of data exceeds this limit but does not exceed the hard limit, a message is printed on the user’s terminal, indicating that her quota has been exceeded; however, the write operation will succeed.
- Per-group hard limit
This is the final limit set for a group by the quota system. Once this limit has been reached, none of the users within that group will be allowed to write files to the disk—even if the user’s individual limits are not exceeded.
- Per-group soft limit
This limit behaves in the same way as a user’s soft limit but is enforced based on group ownership instead of individual ownership.
- Grace period
Once a soft limit is reached, the user or group enters the grace period. After the grace period expires, the soft limit becomes a hard limit until enough files are deleted to eliminate the over-quota situation. The grace period may be specified for any number of months, weeks, days, hours, minutes, or seconds. ...