innobackupex 备份失败并出现以下错误。每次在同一步骤失败时，我都会检查 /var/lib/mysql 下文件的权限，它们都归 mysql 所有。不确定发生了什么变化。你能告诉我们可能是什么问题以及如何解决它吗？
innobackupex: Using server version 10.0.17-MariaDB-wsrep
innobackupex: Created backup directory /backups/xtrabackup/full/2015-04-04_21-43-36/2015-04-04_21-48-14
150404 21:48:14 innobackupex: Starting ibbackup with command: xtrabackup --defaults-group="mysqld" --backup --suspend-at-end --target-dir=/backups/full/2015-04-04_21-43-36/2015-04-04_21-48-14 --innodb_data_file_path="ibdata1:12M:autoextend" --tmpdir=/tmp --extra-lsndir='/tmp'
innobackupex: Waiting for ibbackup (pid=30753) to suspend
innobackupex: Suspend file '/backups/xtrabackup/full/2015-04-04_21-43-36/2015-04-04_21-48-14/xtrabackup_suspended_2'
xtrabackup version 2.2.9 based on MySQL server 5.6.22 Linux (x86_64) (revision id: )
xtrabackup: uses posix_fadvise().
xtrabackup: cd to /var/lib/mysql
xtrabackup: open files limit requested 0, set to 1024
xtrabackup: using the following InnoDB configuration:
xtrabackup: innodb_data_home_dir = ./
xtrabackup: innodb_data_file_path = ibdata1:12M:autoextend
xtrabackup: innodb_log_group_home_dir = ./
xtrabackup: innodb_log_files_in_group = 2
xtrabackup: innodb_log_file_size = 1136656384
>> log scanned up to (372528917742)
xtrabackup: Generating a list of tablespaces
2015-04-04 21:48:14 7f4c0b788720 InnoDB: Operating system error number 24 in a file operation.
InnoDB: Error number 24 means 'Too many open files'.
InnoDB: Some operating system error numbers are described at
InnoDB: http://dev.mysql.com/doc/refman/5.6/en/operating-system-error-codes.html
InnoDB: Error: could not open single-table tablespace file ./LINLEE/tblMiscActivityItems.ibd
InnoDB: We do not continue the crash recovery, because the table may become
InnoDB: corrupt if we cannot apply the log records in the InnoDB log to it.
InnoDB: To fix the problem and start mysqld:
InnoDB: 1) If there is a permission problem in the file and mysqld cannot
InnoDB: open the file, you should modify the permissions.
InnoDB: 2) If the table is not needed, or you can restore it from a backup,
InnoDB: then you can remove the .ibd file, and InnoDB will do a normal
InnoDB: crash recovery and ignore that table.
InnoDB: 3) If the file system or the disk is broken, and you cannot remove
InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf
InnoDB: and force InnoDB to continue crash recovery here.
innobackupex: got a fatal error with the following stacktrace: at /usr/bin/innobackupex line 2704
main::wait_for_ibbackup_file_create('/backups/full/2015-04-04_21-43-36/2015-04-04_21-48...') called at /usr/bin/innobackupex line 2724
main::wait_for_ibbackup_suspend('/backups/full/2015-04-04_21-43-36/2015-04-04_21-48...') called at /usr/bin/innobackupex line 1977
main::backup() called at /usr/bin/innobackupex line 1601
innobackupex: Error: The xtrabackup child process has died at /usr/bin/innobackupex line 2704.