Quota- Linux User Quota HowTo

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USER QUOTA HOWTO

Verifiably applicable to Redhat 7.2 - 9.0 and reasonably 
applicable to any Linux distribution.
___________________________________________________________
                                     Created Sept 2003 v2.0

section A: Ten Steps to User Quotas

1). Do you need to patch your kernel?

• if you are using a recent version of RH with the RH supplied kernel, then no.

2). Do you need to install quota?

• if you are using a recent version of RH with quota installed, then no. The most recent version of quota as of this writing is quota 3.06 - 9.

3.) Modify /etc/fstab and add support for quota on the file system(s) you intend to regulate. Hopefully, when you installed linux you allocated partitions appropriately to benefit the most from user quota implementation.

   example: Adding quota to a mail server, the path
   /var/spool/mail is a seperate partition.  In fstab it
   looked like this prior to modification:

   LABEL=/var/spool/mail  /var/spool/mail  ext3  defaults  1 2

   To enable user quota support on a file system, add 
   "usrquota" to the 4th field containing the word "defaults"

   LABEL=/var/spool/mail  /var/spool/mail  ext3  defaults,userquota  1 2

   Replace "usrquota" with "grpquota", should you need 
   group quota support on a file system.

4.) Since you modified fstab, reboot the computer.

5.) create the necessary files on the partition where you enabled quota. Create the files 'aquota.group' and 'aquota.user'. Activate the quota database.

   example: 'touch /var/spool/mail/aquota.user'
   'touch touch /var/spool/mail/aquota.group'
   'chmod /var/spool/mail/aquota.* 600'
   'quotacheck /var/spool/mail'

6.) Create a cron job to update the quota database. Quota automatically should work with periodical checks, it sometimes helps to run quotacheck periodically.

   example: 0 3 * * 0 /sbin/quotacheck -avug

section B: Syntax and Command Usage

usage:

Assigning quota to a specif user or group is accomplished with the command 'edquota'. To display all quota limits use the command 'repquota'.

   example: 'edquota -u username'
   'repquota -a'

To rapidly set quotas for many users all at once use the following syntax (all users with uid 500 and up). Sets everyone to the same quota as 'username')

   example: edquota -p username `awk -F: '$3 > 499 {print $1}' /etc/passwd`

The commands 'quotaon' turns on quota accounting and 'quotaoff' to turns it off.

definitions:

Soft Limit: usage on filesystem that triggers grace period.

Hard Limit: maximum usage limit before write access is denied to the user.

Grace Period: period triggered by soft limit before access is denied to the user.

Block Limits: total accumulated file disk usage.

File Limits: total number of files or inodes.

section C: Real ISP Implementation Example

intro:

In this example an ISP uses quota to limit the size of customer mailboxes on /var/spool/mail for /dev/sda2.

Disk quotas were enabled using the procedure described above. Now our goals are as follows:

goals:

1. establish default quotas for a mail system already containing 100 or more users.

example: start by setting the first user's quota to the values to be the system default.

  edquota -u derek

second use a simple shell script to duplicate those values to every mailbox owner all at once.

  edquota -p derek `awk -F: '$3 > 499 {print $1}' /etc/passwd

2. synchronize the quota database for the filesystem on /dev/sda2.

example:

  quotaoff /var/spool/mail
  /sbin/quotacheck -avug
  quotaon /var/spool/mail

3. generate a report showing only users exceeding their mailbox disk quota.

example:

  repquota -ta | grep -v "\-\-\ \ \ "

4. configure warnquota to send mail to users over quota by creating or modifying the warnquota.conf file.

example:

  vi /etc/warnquota.conf

use the following values in warnquota.conf

   MAIL_CMD        = "/usr/sbin/sendmail -t"
   FROM            = "support@ispname.com"
   SUBJECT         = NOTE: Your mailbox has exceeded allocatted disk space limits
   CC_TO           = "support@ispname.com"
   SUPPORT         = "support@ispname.com"
   PHONE           = "555 555-1212"
   MESSAGE         = Your mailbox has exceeded the allotted limit\
    on this server|Please delete any unnecessary email in your mailbox on:|
   SIGNATURE       = This message is automatically generated by the mail system.

5. send customers over soft limit an email notification

example:

  warnquota 

6. create a daily cron process script that will synchronize the quota database, send an email notification to mailbox owners exceeding soft quota, and send an email report to the system administrator which includes users exceeding their mailbox disk quota.

example:

  create a cron script, make it executable and add the appropriate shell commands.

  touch /etc/cron.daily/quotatasks
  chmod +x /etc/cron.daily/quotatasks
  vi /etc/cron.daily/quotatasks

shell script example:

#!/bin/bash
#
# Derek B. Winterstien
#######################################
#
/sbin/quotaoff /var/spool/mail
/sbin/quotacheck -avug
/sbin/quotaon /var/spool/mail
sleep 5s
/usr/sbin/warnquota
echo "From: System <null@culverin.ispdomain.com>" > /tmp/mmail.lastmessage.txt
echo "To: recipients@ispdomain.com" >> /tmp/mmail.lastmessage.txt
echo "Subject: cron daily - quotatasks execution" >> /tmp/mmail.lastmessage.txt
echo "Attention:" >> /tmp/mmail.lastmessage.txt
echo "quotatasks executed." >> /tmp/mmail.lastmessage.txt
/bin/date >> /tmp/mmail.lastmessage.txt
echo " " >> /tmp/mmail.lastmessage.txt
echo "System mailbox quota report:" >> /tmp/mmail.lastmessage.txt
echo " " >> /tmp/mmail.lastmessage.txt
echo "Showing only users over disk quota" >> /tmp/mmail.lastmessage.txt
/usr/sbin/repquota -ta | grep -v "\-\-\ \ \ " >> /tmp/mmail.lastmessage.txt
echo " " >> /tmp/mmail.lastmessage.txt
echo "Customers exceeding soft quota have been notified by email." >> /tmp/mmail.lastmessage.txt
echo " " >> /tmp/mmail.lastmessage.txt
echo "System, " >> /tmp/mmail.lastmessage.txt
echo " " >> /tmp/mmail.lastmessage.txt
echo "Derek B. Winterstien" >> /tmp/mmail.lastmessage.txt 
echo " " >> /tmp/mmail.lastmessage.txt
echo "_______________________________________________________________" >> /tmp/mmail.lastmessage.txt
echo "www.ispdomain.com - High Speed Internet Connections To The World" >> /tmp/mmail.lastmessage.txt
echo " " >> /tmp/mmail.lastmessage.txt
echo " " >> /tmp/mmail.lastmessage.txt
#
/usr/sbin/sendmail noc@ispdomain.net,support@ispdomain.net < /tmp/mmail.lastmessage.txt