I installed 3.1.0-9ubuntu1.2 on ubuntu 10.0.04 on /dev/sda1. I have a second disk /dev/sdb1 which is mounted as /mnt/sdb1. I want to backup the server to this second drive. I changed the variable TopDir to be /mnt/sdb1/backups. When I try to run a full backup, I see the following in the log...

2012-03-23 16:14:18 User backuppc requested backup of localhost (localhost)
2012-03-23 16:14:19 localhost: test hardlink between /mnt/sdb1/backups/pc/localhost and /mnt/sdb1/backups/cpool failed
I set the XferMethod to rsync. I excluded /mnt/sdb/backups from the backup.
How do I set up the hardlink?