Disk quota

That is, a system administrator defines a usage or file quota specific to a certain user or group.

This is used, for example, by web hosting companies to provide different levels of service based upon the needs and means of individual clients.

Should an administrator want to limit the usage of a specific user on all file systems, a separate quota would have to be specified on each.

The user is typically notified through the failed write operation error messages generated by the violating applications, while the administrator is almost always sent a notification as well.

Disk quotas are supported by most modern operating systems, including Unix-like systems, such as AIX (using JFS or JFS2 filesystem), Linux (using ext3, ext4, ext2, XFS (integrated support) among other filesystems), Solaris (using UFS or ZFS), Microsoft Windows starting with Windows 2000, Novell NetWare, VMS, and others.