I don't think vzdump works very well on CentOS 6. The creators test it only for Debian. Here an example:
http: //forum.proxmox.com/threads/6857-vzdump-snapshot-works-but-suspend-fails
If you are able to shutdown the container for a minute you could also do an easy LVM snapshot. Which is probably better, since vzdump backups are not 100% safe anyway.
See also post #11
http: //forum.proxmox.com/threads/1946-Active-Standby-with-rsync?p=33952#post33952
(sorry can not post links yet)
[Updated on: Wed, 17 August 2011 00:35]
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