intro.html

Unix下基于Web的管理工具

<header>Disk Quotas</header>

<h3>Introduction</h3>
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. <p>

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. <p>

For each user four limits are imposed :
<dl>
<dt><b>Soft block limit</b>
<dd>The number of disk blocks allowed before a warning message is displayed.
<dt><b>Hard block limit</b>
<dd>The maximum number of blocks that the user's file may occupy.
<dt><b>Soft file limit</b>
<dd>The number of files allowed before a warning message is displayed.
<dt><b>Hard file limit</b>
<dd>The maximum number of files that the user may own.
</dl>
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. <p>

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 <i>inodes</i>. <p>

<h3>The Disk Quotas Module</h3>
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 <tt>Enabled Quotas</tt> will activate quotas for that filesystem. <p>

<if $gconfig{'os_type'} =~ /linux/>
The Linux operating system does not allow quotas to be turned on unless
the filesystem has the <tt>Use Quotas</tt> 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. <p>
</if>

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. <p>

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