mirror of https://github.com/tLDP/LDP
304 lines
12 KiB
Plaintext
304 lines
12 KiB
Plaintext
<!doctype linuxdoc system>
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<article>
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<title>Quota mini-HOWTO
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<author>Ralf van Dooren <tt/r.vdooren@snow.nl/
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<date>v0.5, 2003-08-09
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<abstract>
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Preamble: This document is written by Ralf van Dooren (r.vdooren@snow.nl).
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Original text and setup of this document is copyleft-ed by Albert M.C. Tam, many thanks to him
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for this initial mini-HOWTO.
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This document is licensed under the GNU Free Documentation License.
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Permission to use, copy, distribute this document for non-commercial purposes
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is hereby granted, provided that the author's / editor's name and this notice
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appear in all copies and/or supporting documents; that this document is not
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modified. This document is distributed in hope that it will be useful, but
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WITHOUT ANY WARRANTY, either expressed or implied. While every effort has been
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taken to ensure the accuracy of the information documented herein, the author /
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editor / maintainer assumes NO RESPONSIBILITY for errors, or for damages results
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for the use of the information documented herein.
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This document describes how to enable file system quota on a Linux host,
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assigning quota for users and groups, as well as the usage of miscellaneous
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quota commands. It is intended for users running kernel 2.x (recently tested
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on kernel 2.4.21).
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Feel free to send feedbacks or comments to r.vdooren@snow.nl if you find an
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error, or if any information is missing. I appreciate it.
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</abstract>
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<sect>What is quota?
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<sect1>What is quota for?
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<p>
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Quota allows you to specify limits on two aspects of disk storage: the
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number of inodes a user or a group of users may possess; and the number of
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disk blocks that may be allocated to a user or a group of users.
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<p>
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The idea behind quota is that users are forced to stay under their disk
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consumption limit, taking away their ability to consume unlimited disk space
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on a system. Quota is handled on a per user, per file system basis. If there
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is more than one file system which a user is expected to create files, then
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quota must be set for each file system separately. Various tools are
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available for you to administer and automate quota policies on your
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system.
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<sect1>Current Status of Quota on Linux
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<p>
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Currently, there are some major changes in the way quota works. There are two
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different setups. The tools works the same, but there's a difference in used files. This
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document describes the setup and operation of the _new_ quota setup. As the new setup
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of quota is not in the regular kernel source, this setup needs some patching. We will describe this
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patching and installation of the linuxquota package. If you already have the quota software installed
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on your system, you may or may not have to install this patch and package. You can email me if
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you have any questions about this. I'll try to include a overview of Linux distro's and it's implications
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in a later version of this document.
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<sect>Requirements for quota
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<p>
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<sect1>Kernel
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<p>
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The 2.x kernel source is available from <url
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url="http://www.kernel.org/" name="http://www.kernel.org">
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Please use an available mirror close to your location to save bandwidth. If
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you have a recent version of tar, you can download the .bz2 compressed file.
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Untar the kernel:
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<code>
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cd /usr/src
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tar jxvf /path/to/linux-2.4.21-tar.bz2 - for bzip2 kernel -
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tar zxvf /path/to/linux-2.4.21-tar.gz - for gzip kernel -
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ln -s /usr/src/linux-2.4.21 /usr/src/linux
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</code>
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<sect1>Quota software
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<p>
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Depending on the Linux distribution you have, you may, or may not have
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the quota softwares installed on your system. The most recent version of quota
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is available through SourceForge and is in active development. You can reach the
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homepage of the quota-development at <url
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url="http://www.sourceforge.net/project/linuxquota"
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name="http://www.sourceforge.net/projects/linuxquota" >.
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<sect>Quota setup: installation and configuration
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<sect1>Patch the kernel
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<p>Download the patch for your kernel at:
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<url url="ftp://atrey.karlin.mff.cuni.cz/pub/local/jack/quota/"
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name="ftp::/atrey.karlin.mff.cuni.cz/pub/local/jack/quota/" >.
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<p>
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Choose your kernel version and download the patch(es). Patch your kernel with the 'patch' command. If there is more than 1 patch for your kernel version, be sure to apply the patches in the correct order.
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You can use this script ( I assume the downloaded patches are in /tmp/quota/ and the kernel has been untarred to /usr/src/linux) :
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<code>
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#!/bin/sh
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gunzip /tmp/quota/*.gz
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cd /usr/src/linux
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COUNT=`ls -1 /tmp/quota/*.diff | wc -l`
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for I in `seq 1 $COUNT`
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do
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patch -p1 < /tmp/quota/quota-2.4.21-$I-*.diff
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done
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</code>
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<sect1>Reconfigure your kernel
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<p>
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Reconfigure your kernel and add quota support.
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<p>Via `make menuconfig` or `make xconfig` you can find the option to support quota under the Filesystems-menu. You can specify extra options if you need them, like 32-bit UID support.
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<p>Save the configuration and compile the kernel. Make sure the new kernel will be used when rebooting the system.
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<sect1>Compile and install the quota softwares
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<p>
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To be able to use all the features of the new quota system, you'll probably need to download the new quota-package. Download the new quota software via the URL
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provided above.
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<p>
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When downloaded do:
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<code>$ gzip -dc <downloaded file> | tar xvf
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$ cd quota-tools (or whatever directory the software is put in)
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$ ./configure
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$ make
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$ su
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# make install
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</code>
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<sect1>Modify your system init script to check quota and turn quota on at boot
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time
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<p>
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Here's an example:
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<code># Check quota and then turn quota on.
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if [ -x /usr/sbin/quotacheck ]
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then
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echo "Checking quotas. This may take some time."
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/usr/sbin/quotacheck -avug
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echo " Done."
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fi
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if [ -x /usr/sbin/quotaon ]
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then
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echo "Turning on quota."
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/usr/sbin/quotaon -avug
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fi
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</code>
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The golden rule is that always turn quota on after your file systems in
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/etc/fstab have been mounted, otherwise quota will fail to work. I recommend
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turning quota on right after the part where file systems are mounted in your system init script.
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<sect1>Modify /etc/fstab
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<p>
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Partitions that you have not yet enabled quota normally look something
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like:
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<code>/dev/hda1 / ext2 defaults 1 1
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/dev/hda2 /usr ext2 defaults 1 1
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</code>
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To enable user quota support on a file system, add "usrquota" to the fourth
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field containing the word "defaults" (man fstab for details).
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<code>/dev/hda1 / ext2 defaults 1 1
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/dev/hda2 /usr ext2 defaults,usrquota 1 1
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</code>
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Replace "usrquota" with "grpquota", should you need group quota support
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on a file system.
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<code>/dev/hda1 / ext2 defaults 1 1
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/dev/hda2 /usr ext2 defaults,grpquota 1 1
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</code>
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Need both user quota and group quota support on a file system?
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<code>/dev/hda1 / ext2 defaults 1 1
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/dev/hda2 /usr ext2 defaults,usrquota,grpquota 1 1
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</code>
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<sect1>Activate the quota system
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<p>
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To activate the quota software you have to reboot the system for the changes you have made
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to take effect. The new kernel with quota support will be loaded and the startup scripts you've
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just created will be executed. At first run, quotacheck will generate the appropiate files to maintain
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the quota databases.
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<sect1>Add quotacheck to crontab
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<p>
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Although quota should work with periodical checks, it sometimes helps to run quotacheck periodically, e.g. weekly. Add the following line to your root's crontab:
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<code>0 3 * * 0 /sbin/quotacheck -avug
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</code>
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<sect>Quota setup: tools
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<p>
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This operation is performed with the edquota command (`man edquota` for details).
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<sect1>Assigning quota for a particular user
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<p>
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Here's an example. I have a user with the login id bob on my system. The
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command "edquota -u bob" takes me into vi (or editor specified in my $EDITOR
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environment variable) to edit quota for user bob on each partition that has
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quota enabled:
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<code>Quotas for user bob:
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/dev/hda3: blocks in use: 2594, limits (soft = 5000, hard = 6500)
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inodes in use: 356, limits (soft = 1000, hard = 1500)
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</code>
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"blocks in use" is the total number of blocks (in kilobytes) a user has
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consumed on a partition.
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"inodes in use" is the total number of inodes a user has consumed on a partition.
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<sect1>Assigning quota for a particular group
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<p>
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Now I have a group games on my system. "edquota -g games" takes me into
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the vi editor again to edit quota for the group games:
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<code> Quotas for group games:
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/dev/hda4: blocks in use: 5799, limits (soft = 8000, hard = 10000)
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inodes in use: 1454, limits (soft = 3000, hard = 4000)
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</code>
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<sect1>Assigning quota for a bunch of users with the same value
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<p>
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To rapidly set quotas for, say 100 users, on my system to the same value
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as my user bob, I would first edit bob's quota information by hand, then execute:
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<code>edquota -p bob `awk -F: '$3 > 499 {print $1}' /etc/passwd`
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</code>
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assuming that you are using csh, and that you assign your user UID's starting
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with 500.
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In addition to edquota, there are 3 terms which you should familiarize
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yourself with: Soft Limit, Hard Limit, and Grace Period.
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<sect1>Soft Limit
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<p>
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_Soft limit_ indicates the maximum amount of disk usage a quota user has
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on a partition. When combined with grace period, it acts as the border line,
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which a quota user is issued warnings about his impending quota violation when
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passed.
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<sect1>Hard Limit
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<p>
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Hard limit works only when grace period is set. It specifies the absolute
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limit on the disk usage, which a quota user can't go beyond his hard limit.
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<sect1>Grace Period
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<p>
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Executed with the command "edquota -t", grace period is a time limit before
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the soft limit is enforced for a file system with quota enabled. Time units
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of sec(onds), min(utes), hour(s), day(s), week(s), and month(s) can be used.
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This is what you'll see with the command "edquota -t":
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<code>Time units may be: days, hours, minutes, or seconds
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Grace period before enforcing soft limits for users:
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/dev/hda2: block grace period: 0 days, file grace period: 0 days
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</code>
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Change the 0 days part to any length of time you feel reasonable. I personally
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would choose 7 days (or 1 week).
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<sect>Miscellaneous Quota Commands
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<p>
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<sect1>Quotacheck
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<p>
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Quotacheck is used to scan a file system for disk usages, and updates the
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quota record file "aquota.user" to the most recent state. I recommend running
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quotacheck at system bootup, and via cronjob periodically (say, every week?).
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<sect1>Repquota
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<p>
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Repquota produces a summarized quota information for a file system. Here
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is a sample output repquota gives:
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<code># repquota -a
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Block limits File limits
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User used soft hard grace used soft hard grace
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root -- 175419 0 0 14679 0 0
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bin -- 18000 0 0 735 0 0
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uucp -- 729 0 0 23 0 0
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man -- 57 0 0 10 0 0
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user1 -- 13046 15360 19200 806 1500 2250
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user2 -- 2838 5120 6400 377 1000 1500
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</code>
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<sect1>Quotaon and Quotaoff
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<p>
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Quotaon is used to turn on quota accounting; quotaoff to turn it off. Actually
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both files are similar. They are executed at system startup and shutdown.
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</article>
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