Disk Quotas

Introduction

Quotas are a method of controlling how much disk space users and groups can use. For each filesystem you can place limits on how much disk space and how many files each user may use. Some Unix systems may also allow you to limit the space and files used by all members of some group.

Quotas can only be setup for local Unix filesystems. NFS filesystems mounted from other systems use the quotas from the server, if any. Non Unix filesystems like MS-DOS or ISO9660 cannot support quotas at all.

For each user four limits are imposed :

Soft block limit
The number of disk blocks allowed before a warning message is displayed.
Hard block limit
The maximum number of blocks that the user's file may occupy.
Soft file limit
The number of files allowed before a warning message is displayed.
Hard file limit
The maximum number of files that the user may own.
Disk blocks are typically 512 or 1024 bytes in size, depending on the operating system. When computing quotas, all file sizes are rounded up to the nearest block. Thus even an empty file uses at least on block.

For the purpose of file quotas, every directory, device, symbolic link or normal file counts towards the maximum number of files a user may own. Technically, the file quota is actually a quota on inodes.

The Disk Quotas Module

The main page of this module shows a list of local filesystems that can support quotas. If quotas are currently enabled for a filesystem, you may click on its path to display the quotas for each user. If not, clicking on Enabled Quotas will activate quotas for that filesystem.

The Linux operating system does not allow quotas to be turned on unless the filesystem has the Use Quotas option set in the Disks and Filesystems module. If none of your filesystems have this option set then none will be listed on the main page.

Below the list of filesystems is a button for displaying all quotas for a selected user. This will only be displayed if at least one filesystem has user quotas enabled. Similarly, if at least one filesystem has group quotas enabled there will be a button for displaying all quotas for a selected group.