Percona xtrabackup Prepare Fails I made a backup and according to Percona it completed successfully.  Now I'm trying to prepare it and having the following issue:

./xtrabackup_55  --defaults-file="/etc/my.cnf"  --defaults-group="mysqld" --prepare --target-dir=/backup/unprepared/2013_05_21_21_31_41_full
xtrabackup: cd to /backup/unprepared/2013_05_21_21_31_41_full
xtrabackup: This target seems to be not prepared yet.
xtrabackup: No valid checkpoint found.
xtrabackup: Error: xtrabackup_init_temp_log() failed.


I've been searching for answers for quite a while and not finding anything conclusive.  Any advice on how to resolve this?



Edit: per comment below, here is requested info:

xtrabackup_55 version 2.0.3 for Percona Server 5.5.16 Linux (x86_64) (revision id: 470)

cat /etc/my.cnf|grep innodb
innodb_data_home_dir = /data/mysql_data/
innodb_data_file_path = ibdata1:2000M;ibdata2:10M:autoextend
innodb_log_group_home_dir = /var/mysql/data/
innodb_file_per_table
innodb_buffer_pool_size = 5G
innodb_additional_mem_pool_size = 40M
innodb_log_file_size = 1G
innodb_log_buffer_size = 16M
innodb_log_block_size = 512
innodb_flush_log_at_trx_commit = 1
innodb_lock_wait_timeout = 50
innodb_thread_concurrency = 8
innodb_doublewrite_file = /var/mysql/innodb_doublewrite.buff
innodb_flush_method = ALL_O_DIRECT
Percona xtrabackup documentation indicates that you should point xtrabackup_55 to the backup-my.cnf file taken with your backup, rather than your live my.cnf file.

If you're doing the prep on the same server as the backup was taken, I'm not sure if it will make a difference.