Error: DUMP: You can't update the dumpdates file when dumping a subdirectory DUMP: The ENTIRE dump is aborted

Error accurs when amdump is started against a Xen Client and using dump instead of tar in the dumptype:

START driver date 20060525
DISK planner www.zmanda.com /var/www/html
START planner date 20060525
INFO planner Adding new disk www.zmanda.com:/var/www/html.
STATS driver startup time 0.010
START taper datestamp 20060525 label web_services_backup05 tape 0
FINISH planner date 20060525 time 1.124
FAIL dumper www.zmanda.com /var/www/html 20060525 0 [/sbin/dump returned 1]
 sendbackup: start [www.zmanda.com:/var/www/html level 0]
 sendbackup: info BACKUP=/sbin/dump
 sendbackup: info RECOVER_CMD=/usr/bin/gzip -dc |/sbin/restore -f... -
 sendbackup: info COMPRESS_SUFFIX=.gz
 sendbackup: info end
 |   DUMP: You can't update the dumpdates file when dumping a subdirectory
 |   DUMP: The ENTIRE dump is aborted.
 sendbackup: error [/sbin/dump returned 1]
INFO taper tape web_services_backup05 kb 0 fm 0 [OK]
FINISH driver date 20060525 time 16.238

The cause of this problem is that dump -u does not work correctly on Xen clients and therefore can't update /etc/dumpdates file. This cause admump to abort.

The solution is to use tar instead of dump when backing up Xen clients.