Disk Limits and Quota

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We call Disk Limit a disk space limit in a filesystem for one context (i.e. VServer). If you are interested in using user/group quotas inside a VServer, this is not the right place, look at the Quotas page.

Of course, you can also use a dedicated partition (or logical volume) for each guest, which is another way to limit disk space usage per guest.

Activating disk limits

For VServer version 2.0, please read http://oldwiki.linux-vserver.org/Disk+Limits

For VServer 2.2+, the procedure is nearly the same, only the mount option has changed:

  1. Activate the XID tagging on the filesystem hosting the VServer, using the tag mount option. You cannot use the remount option to add the tag on an already mounted filesystem. Be warn, it is not advised to use it on the root filesystem! In the next example, we use the /dev/sdb1 partition to host all the guests, under the /vservers directory
    mount -o tag /dev/sdb1 /vservers
  2. Consider modifying your /etc/fstab file if necessary, to make the mount option persist across reboots
  3. Tag the files belonging to the VServer with its XID
    chxid -URx -c vs_name /vservers/vs_name 
  4. Write the limits under the /etc/vservers/vs_name/dlimits directory :
    1. Create this directory if necesary
    2. Create one sub-directory for each filesystem (in most cases, you should have only one), using any identifier (for example root)
    3. Under /etc/vservers/vs_name/dlimits/root/ create the following files :
      1. directory : contains the directory to which the limit should be applied
      2. inodes_total : the amount of inodes this vserver should be limited to
      3. reserved : how much space (percentage-wise) should be reserved for the root user
      4. space_total : the amount of space this vserver should be limited to (measured in blocks of 1024 bytes)

Controling disk limits

After starting your VServer, you can control the actual limit using the vdlimit command (in this example, 300 is the context number associated with vs_name) :

 # vdlimit --xid vs_name /vservers
 300 /vservers

You can also use the vdu command to count space or inodes used by a specific guest

 # vdu --xid vs_name --space /vservers
 /vservers 154604
 # vdu --xid vs_name --inodes /vservers
 /vservers 7834

If you just want update disk usage of a guest after setting the limits you can use this script. It will count usage of all files and update the limits:

 if [ ! -d $_dir/$1 ]; then
     echo no such vserver
     exit 1;
 chxid -URx -c $1 $_dir/$1
 vdlimit --xid $1 -s space_used=$(vdu --xid $1 --space $_dir/$1 | cut -d" " -f2) $_dir/$1
 vdlimit --xid $1 -s inodes_used=$(vdu --xid $1 --inode $_dir/$1 | cut -d" " -f2) $_dir/$1

Removing disk limits

To remove disk limits, remove the /etc/vservers/vs_name/dlimits/root directory and remove the limits with the following command

 # vdlimit --xid vs_name --remove /vservers

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