How to implement Quotas on your system
From FedoraNEWS.ORG
Written by Anze Vidmar on 2005-09-18
| Table of contents |
About
Quota allows you to specify limits on two aspects of disk storage: the number of inodes a user or a group of users may possess; and the number of disk blocks that may be allocated to a user or a group of users.
Why do I need Quota?
Let's say you have a nice multi-user server and accounts on it for your friends/family members... Now, since you don't want this server to be running out of disk space, because all your users that are using your system are downloading stuff from the internet, you simply limit the disk space that they can use.
Preparations
Quotas are simple to setup and maintain. FC4 comes already with "built-in" support for Quota, so let's start configuring. In my case, I'll setup Quotas on /home part of the system, and I will limit user Dasa to only allow her use 4Mb of disk space.
Configuration
First, you need to edit the /etc/fstab file. Look in yout /etc/fstab file for line about /home
LABEL=/home /home ext3 defaults 1 2
And add the "usrquota" to the options:
LABEL=/home /home ext3 defaults,usrquota 1 2
Next, you need to remount the filesystem mounted on /home, for changes to take effect. This can be done with
[root@localhost ~]# mount -o remount /home
Next, you need to create the file in which the quota info will be written in. This is done by
[root@localhost ~]# touch /home/aquota.user [root@localhost ~]# chmod 600 /home/aquota.user
Note, that if you like to setup group-based quotas, you also need to create aquota.group file.
Remember, you must always create aquota file(s) on the uppermost directory of the filesystem, in our case /home.
Next, it's time to initialize the Quota table. This is done by
[root@localhost ~]# quotacheck -vagum
You will get an error complaining about missing file, but this is totaly normal for the 1st time Quota initialization. The error will look like this
[root@localhost ~]# quotacheck -vagum quotacheck: WARNING - Quotafile /home/aquota.user was probably truncated. Can't save quota settings... quotacheck: Scanning /dev/hda5 [/home] done quotacheck: Checked 4 directories and 26 files [root@localhost ~]#
At this point, the Quota is up and running. Now it's time to define some disk limitations. For this purpose, the edquota tool is used.
Let's setup the Quota for user Dasa now:
[root@localhost ~]# edquota -u Dasa
The vi editor is starts and we end up with Quota table, looking like this
Disk quotas for user Dasa (uid 500): Filesystem blocks soft hard inodes soft hard /dev/hda5 16 0 0 0 0 0
The first three objects (blocks, soft and hard) applies to Block Limits, and the second 3 objects (inodes, soft and hard) applies to File limits.
Since, we want user Dasa to be limited to the particular size (4Mb), we will edit Block lines. The first "Blocks" line tells us how much of the disk space for user Dasa is already taken. So all we need is to setup the hard limit.
Note that soft limit is used when you want to have grace time for Quota and hard limit is used when grace period is set to 0.
So, after editing the Quota table, our table looks like this
Disk quotas for user Dasa (uid 500): Filesystem blocks soft hard inodes soft hard /dev/hda5 16 0 4000 5 0 0
Note that values for Blocks are in kb (kilobytes).
This is it, save the Quota table by writing the changes and exiting the vi editor.
If you want to use grace times, use the same tool with different switch. But keep in mind that in FC4 the deafault grace time is 7days.
[root@localhost ~]# edquota -t
The table looks like this
Grace period before enforcing soft limits for users: Time units may be: days, hours, minutes, or seconds Filesystem Block grace period Inode grace period /dev/hda5 7days 7days
So, if you don't want grace time, change number 7 to 0 and save the table.
After making any Quota changes, you don't need to restart anything, the changes are applied immediately.
You can check the Quota statistics any time with
[root@localhost ~]# repquota /home
As you can see, the Quota stats are very nice shown in the table
[root@localhost ~]# repquota /home/
*** Report for user quotas on device /dev/hda5
Block grace time: 00:00; Inode grace time: 00:00
Block limits File limits
User used soft hard grace used soft hard grace
----------------------------------------------------------------------
root -- 35436 0 0 5 0 0
anze -- 24 0 9000 3 0 0
basinac -- 2783 0 25000 56 0 0
Dasa -- 16 0 4000 5 0 0
Pokemon -- 16 0 50000 3 0 0
Izo -- 20 0 500000 4 0 0
[root@localhost ~]#
Test
Now, let's login from ssh or console (or whatever you prefer) as user Dasa. When logged in, user Dasa can check her Quota limit by entering the command
[Dasa@localhost ~]$ quota
She will see something like this
[Dasa@localhost ~]$ quota
Disk quotas for user Dasa (uid 501):
Filesystem blocks quota limit grace files quota limit grace
/dev/hda3 16 0 4000 5 0 0
[Dasa@localhost ~]$
Ok, this is correct. Now, let's test it, by downloading the xmms rpm file (that is 5Mb large) from rpmfind.net
[Dasa@localhost ~]$ wget ftp://rpmfind.net/linux/fedora/core/3/SRPMS/xmms-1.2.10-9.src.rpm
The file will start downloading, and if we set the Quota correct, it should cut-off the file that is downloading when size reaches to 4Mb.
This looks like this
[Dasa@localhost ~]$ wget ftp://rpmfind.net/linux/fedora/core/3/SRPMS/xmms-1.2.10-9.src.rpm
--02:06:11-- ftp://rpmfind.net/linux/fedora/core/3/SRPMS/xmms-1.2.10-9.src.rpm
=> `xmms-1.2.10-9.src.rpm'
Resolving rpmfind.net... 194.199.20.114, 195.220.108.108
Connecting to rpmfind.net[194.199.20.114]:21... connected.
Logging in as anonymous ... Logged in!
==> SYST ... done. ==> PWD ... done.
==> TYPE I ... done. ==> CWD /linux/fedora/core/3/SRPMS ... done.
==> PASV ... done. ==> RETR xmms-1.2.10-9.src.rpm ... done.
Length: 5,290,751 (unauthoritative)
73% [==============================================================> ] 3,878,592 1.41M/s
hda5: write failed, user block limit reached.
77% [=======================================================================> ] 4,089,264 1.42M/s
xmms-1.2.10-9.src.rpm: Disk quota exceeded, closing control connection.
[Dasa@localhost ~]$
And if we check the space usage in her home folder, we will see that all 4M are used and no more fun for user Dasa.
[Dasa@localhost ~]$ du -h 4.0M . [Dasa@localhost ~]$
This is it. Quotas are great thing to implemenet on your multi-user box. Use it wisely :)
