set global innodb_fast_shutdown=0;
# restart: --innodb_undo_tablespaces=2
CREATE TABLE t1(a varchar(60)) ENGINE INNODB;
start transaction;
INSERT INTO t1 VALUES(1);
# xtrabackup backup
# Restart the server with 4 undo tablespaces
set global innodb_fast_shutdown=0;
# restart: --innodb_undo_tablespaces=4
# incremental backup should fail
FOUND 1 /--incremental backup is impossible if the server had been restarted with different innodb_undo_tablespaces/ in backup.log
# Take full backup again
# Prepare full backup
# Display 4 undo log files from target directory
undo001
undo002
undo003
undo004
DROP TABLE t1;