如下所示，使用tar -zxvf解压文件时遇到”gzip: stdin: not in gzip format“等错误：
[root@DB-Server tmp]#
[root@DB-Server tmp]# tar -zxvf Percona-XtraBackup-2.2.12-r8726828-el5-x86_64-bundle.tar
gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error exit delayed from previous errors
最终发现这个压缩包没有用gzip格式压缩，所以不用加z参数，汗颜！
[root@DB-Server tmp]# tar -xvf Percona-XtraBackup-2.2.12-r8726828-el5-x86_64-bundle.tar
percona-xtrabackup-2.2.12-1.el5.x86_64.rpm
percona-xtrabackup-debuginfo-2.2.12-1.el5.x86_64.rpm
percona-xtrabackup-test-2.2.12-1.el5.x86_64.rpm
You have new mail in /var/spool/mail/root
[root@DB-Server tmp]#
