When restoring a mysql backup from Percona’s Xtrabackup, there’s a few things to remember. First, be sure to include the -i flag while extracting the tar archive. Second, the backup needs apply the xtrabackup_logfile to play back the binary log and catch back up to the time of the snapshot.

pv backup.tar.gz | tar xivf - -C /var/lib/mysql-incoming
innobackupex --use-memory=1G --apply-log /var/lib/mysql-incoming

Now replace the current mysql directory with this backup and change the ownership accordingly.

mv /var/lib/mysql /var/lib/mysql.old
mv /var/lib/mysql-incoming /var/lib/mysql
chown -R mysql. /var/lib/mysql