VS Secure Quota HowTo

How to use Secure Quota Support for VS

Quota on a separate partition (LVM, vroot, Conv. Quota)

This is an example for setting up quota support for a VServer based
system. It tries to explain how to setup user/group quota on a separate
partition. If you want to use context quota support on a shared partition,
have a look at the Context Quota HowTo.

The following walkthrough was done on a Mandrake 8.2 Linux system,
running a custom built 2.4.20rc1 kernel, patched with CTX-14 patches
from the 0.21 release of VServer, and the vroot01 kernel patch from the
vquota-tools-0.1 package. Packages installed: 0.21 vserver base/admin,
quota-tools 3.07 and the vquota-tools 0.1 vrsetup.

In this example, /dev/vg is the LVM volume group providing the
separate partition /dev/vg/part1 for the to-be-moved virtual server
TE01, and /dev/vroot/0 is the virtual root device used.

The last section provides links to all required patches and tools.

  1. Prerequisites

    You will require at least the following to use/enable quota
    support on your system:

    • quota support for the filesystem you want to use.
    • a patched kernel (quota, vserver, vroot, lvm?)
    • the quota-tools compiled for this kernel.
    • the vquota-tools compiled for this kernel.
    • a free partition, the size for one virtual server.
    • a good idea what quota is, and how to use the tools.

  2. Required Modifications

    You have to patch the kernel to support the CAP_QUOTACTL
    capability and provide the vroot (fake) device. Further you
    will need the CAP_QUOTACTL aware vserver tools, and the
    vrsetup tool to configure the vroot device.

  3. Server Setup/Move

    This step assumes that you want to move your existing virtual
    server TE01 on a separate partition /dev/vg/part1, and enable
    quota support for that partition. If you either do not have an
    existing server or already moved/created one on a separate
    partition, you have to adjust and/or leave out the appropriate
    steps.

    1. stop the virtual server 
      # vserver TE01 stop
    2. create filesystem and mountpoint 
      # mke2fs -j /dev/vg/part1
# mkdir /vservers/LV01
# mount /dev/vg/part1 /vservers/LV01
    3. copy the virtual server and the configuration 
      # cp -a /vservers/TE01/. /vservers/LV01/
# cp -a /etc/vservers/TE01.conf /etc/vservers/LV01.conf
    4. create/modify the start/stop scripts 
      ----------------- /etc/vservers/LV01.sh -----------------
#!/bin/sh
case $1 in
pre-start)
	e2fsck -p /dev/vg/part1
	mount /dev/vg/part1 /vservers/LV01
	rm -f /vservers/LV01/dev/hdv1
	vrsetup /dev/vroot/0 dev/vg/part1
	cp -fa /dev/vroot/0 /vservers/LV01/dev/hdv1
	;;
post-start)
	;;
pre-stop)
	;;
post-stop)
	mount -o remount,ro /vservers/LV01
	umount /vservers/LV01
	vrsetup -d /dev/vroot/0
	;;
*)
	echo $0 pre-start
	echo $0 pre-stop
	echo $0 post-start
	echo $0 post-stop
	;;
esac
----------------- /etc/vservers/LV01.sh -----------------
    5. change the server mtab file 
      /dev/hdv1 / ext3 rw,usrquota,grpquota 0 0
    6. if not already done, install the quota-tools for the virtual server 
      # vrpm LV01 -- -i quota-3.07-1.i586.rpm
    7. start the server and change into it 
      # vserver LV01 start
# vserver LV01 enter
    8. run the quotacheck tool 
      # quotacheck -maug
    9. take a look at the quota report 
      # repquota -aug
    
*** Report for user quotas on device /dev/hdv1
Block grace time: 7days; Inode grace time: 7days
 		      Block limits	       File limits
User            used  soft  hard  grace  used  soft  hard  grace
----------------------------------------------------------------
root      --  249712     0     0	12146	  0	0
rpm       --   13124     0     0	   71	  0	0
apache    --     980     0     0	  235	  0	0
rpcuser   --       4     0     0	    1	  0	0

*** Report for group quotas on device /dev/hdv1
Block grace time: 7days; Inode grace time: 7days
 		      Block limits             File limits
Group           used  soft  hard  grace  used  soft  hard  grace
----------------------------------------------------------------
root      --  248964     0     0        12102	  0	0
daemon    --       4     0     0            1	  0	0
tty       --      16     0     0            2	  0	0
...
    10. use edquota to set and quota to report quota status
    11. live happily ever after using quota wisely ...

  4. Advantages and Disadvantages

    This approach has several advantages and a few drawbacks.
    Advantages would/could be:

    • fixed maximum hard limit for each virtual server.
    • no security/access issues with files or partitions.
    • all quota settings can be done within the server.

    Disadvantages would/could be:

    • no unification across servers is possible.
    • changing the maximum size requires fs/partition resize.
    • filesystem caching is done for each partition.

  5. Patches, Tools, Links ...


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©2002 Herbert Pötzl