That is the correct place for backups. I've been urged by a couple senior zenoss folks not to use the zenbackup/zenrestore functionality in version 3.x though. They say it works fine in 4.x, but has some issues in 3.x. I did test it for myself and it failed on the restore operation. A manual backup may be better.
Do you have the 3.2 on RHEL6 running?