Package percona-xtrabackup-21.x86_64 is also crashing:

InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oy
and Percona LLC and/or its affiliates 2009-2013.  All Rights Reserved.

This software is published under
the GNU GENERAL PUBLIC LICENSE Version 2, June 1991.

Get the latest version of Percona XtraBackup, documentation, and help resources:
http://www.percona.com/xb/p

IMPORTANT: Please check that the apply-log run completes successfully.
           At the end of a successful apply-log run innobackupex
           prints "completed OK!".



141020 15:13:45  innobackupex: Starting ibbackup with command: xtrabackup_56  --defaults-file="/...../10-20-2014_15-07-38/backup-my.cnf"  --defaults-group="mysqld" --prepare --target-dir=/...../10-20-2014_15-07-38 --use-memory=1G --tmpdir=/tmp

xtrabackup_56 version 2.1.9 for MySQL server 5.6.17 Linux (x86_64) (revision id: 746)
xtrabackup: cd to /mnt/backup/client_dbs_innodb/db20-slave/10-20-2014_15-07-38
xtrabackup: This target seems to be not prepared yet.
xtrabackup: xtrabackup_logfile detected: size=2097152, start_lsn=(125029042395)
xtrabackup: using the following InnoDB configuration for recovery:
xtrabackup:   innodb_data_home_dir = ./
xtrabackup:   innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup:   innodb_log_group_home_dir = ./
xtrabackup:   innodb_log_files_in_group = 1
xtrabackup:   innodb_log_file_size = 2097152
xtrabackup: using the following InnoDB configuration for recovery:
xtrabackup:   innodb_data_home_dir = ./
xtrabackup:   innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup:   innodb_log_group_home_dir = ./
xtrabackup:   innodb_log_files_in_group = 1
xtrabackup:   innodb_log_file_size = 2097152
xtrabackup: Starting InnoDB instance for recovery.
xtrabackup: Using 1073741824 bytes for buffer pool (set by --use-memory parameter)
InnoDB: Using atomics to ref count buffer pool pages
InnoDB: The InnoDB memory heap is disabled
InnoDB: Mutexes and rw_locks use GCC atomic builtins
InnoDB: Compressed tables use zlib 1.2.3
InnoDB: Using CPU crc32 instructions
InnoDB: Initializing buffer pool, size = 1.0G
InnoDB: Completed initialization of buffer pool
InnoDB: Highest supported file format is Barracuda.
InnoDB: Log scan progressed past the checkpoint lsn 125029042395
InnoDB: Database was not shutdown normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages
InnoDB: from the doublewrite buffer...
InnoDB: Doing recovery: scanned up to log sequence number 125029793146 (40%)
InnoDB: Starting an apply batch of log records to the database...
InnoDB: Progress in percent: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
InnoDB: Apply batch completed
InnoDB: Last MySQL binlog file position 0 18619084, file name mysql-bin.000154
InnoDB: 128 rollback segment(s) are active.
InnoDB: Waiting for purge to start
InnoDB: 5.6.17 started; log sequence number 125029793146

[notice (again)]
  If you use binary log and don't use any hack of group commit,
  the binary log position seems to be:
InnoDB: Last MySQL binlog file position 0 18619084, file name mysql-bin.000154

xtrabackup: starting shutdown with innodb_fast_shutdown = 1
innobackupex: Error:
innobackupex: ibbackup failed at /usr/bin/innobackupex line 2560.