Issues creating full backup with XtraBackup

I have just installed Percona Xtrabackup on my RHEL5 server and am trying to have it create a full backup from the command line.

From the website ( http://www.percona.com/doc/percona-xtrabackup/howtos/recipes _xbk_full.html), the command to create a backup is “xtrabackup --backup --target-dir=/data/backups/mysql/”

As my database is in a different directory, I’m using the command “xtrabackup --backup --target-dir=/data/backups/mysql/ --datadir=/opt/easyCMDB/amp/mysql/data/”

Is this correct? For some reason it is giving the below error:

================================================
xtrabackup version 2.0.0 for Percona Server 5.1.59 pc-linux-gnu (i686) (revision id: 417)
xtrabackup: uses posix_fadvise().
xtrabackup: cd to /opt/easyCMDB/amp/mysql/data/
xtrabackup: Target instance is assumed as followings.
xtrabackup: innodb_data_home_dir = ./
xtrabackup: innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup: innodb_log_group_home_dir = ./
xtrabackup: innodb_log_files_in_group = 2
xtrabackup: innodb_log_file_size = 5242880
InnoDB: Error: log file ./ib_logfile0 is of different size 0 67108864 bytes
InnoDB: than specified in the .cnf file 0 5242880 bytes!

The xtrabackup help page says you can define the log file size using “xtrabackup --backup --target-dir=/data/backups/mysql/ --datadir=/opt/easyCMDB/amp/mysql/data/ --innodb_log_file_size=67108864”, so I tried that but it just gave me another error:

================================================
xtrabackup version 2.0.0 for Percona Server 5.1.59 pc-linux-gnu (i686) (revision id: 417)
xtrabackup: uses posix_fadvise().
xtrabackup: cd to /opt/easyCMDB/amp/mysql/data/
xtrabackup: Target instance is assumed as followings.
xtrabackup: innodb_data_home_dir = ./
xtrabackup: innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup: innodb_log_group_home_dir = ./
xtrabackup: innodb_log_files_in_group = 2
xtrabackup: innodb_log_file_size = 67108864
120627 16:40:07 InnoDB: Warning: allocated tablespace 1820, old maximum was 9
xtrabackup: Can’t create/write to file ‘/data/backups/mysql/xtrabackup_logfile’ (Errcode: 17)
xtrabackup: error: cannot open /data/backups/mysql/xtrabackup_logfile (errno: 17)

The file ‘/data/backups/mysql/xtrabackup_logfile’ is chmod 777, so it should be writable and readable so I’m not sure what’s going on there.

Can anybody suggest what might be happening? If any further information is required I’ll supply it is possible.

Thanks!

Can anybody shed any light on this?