“File System on Control Domain Full”,“2”,“Disk usage for the Control Domain on server 'xxxxxx' has reached 92.0%. XenServer's performance will be critically affected if this disk becomes full. Log files or other non-essential (user created) files should be removed.

xe patch-destroy uuid=

http://discussions.citrix.com/topic/351235-low-disk-space-dom0/

delete the files in /var/patch – those are old hotfix files

XenCenterでVM→Install Xen Server Tools

# mount /dev/xvdd /mnt
 OR
# mount /dev/cdrom /mnt

# cd /mnt
# cd Linux
# ./install.sh
Detected `CentOS release 6.x (Final)' (centos version 6).

The following changes will be made to this Virtual Machine:
  * update arp_notify sysctl.conf.
  * packages to be installed/upgraded:
    - xe-guest-utilities-6.xxxxx.x86_64.rpm
    - xe-guest-utilities-xenstore-6.xxxxx.x86_64.rpm

Continue? [y/n] y

準備中...                ########################################### [100%]
   1:xe-guest-utilities-xens########################################### [ 50%]
   2:xe-guest-utilities     ########################################### [100%]

You should now reboot this Virtual Machine.
# cd 
# umount /mnt