mariabackup based on MariaDB server 10.2.9-MariaDB Linux (x86_64) 
xtrabackup: cd to /storage/db/backup/xtrabackup_backupfiles/
Loading encryption plugin
	 Encryption plugin parameter :  '--server-id=1'
	 Encryption plugin parameter :  '--slow_query_log=1'
	 Encryption plugin parameter :  '--log_output=table'
	 Encryption plugin parameter :  '--log_slow_verbosity=explain'
	 Encryption plugin parameter :  '--long_query_time=10.0'
	 Encryption plugin parameter :  '--log-error'
	 Encryption plugin parameter :  '--log-warnings'
	 Encryption plugin parameter :  '--binlog-format=ROW'
	 Encryption plugin parameter :  '--log-basename=mariadb-10'
	 Encryption plugin parameter :  '--sync-binlog=1'
	 Encryption plugin parameter :  '--log_bin_trust_function_creators=1'
	 Encryption plugin parameter :  '--expire_logs_days=14'
	 Encryption plugin parameter :  '--thread_cache_size=100'
	 Encryption plugin parameter :  '--max_connections=2000'
	 Encryption plugin parameter :  '--max_binlog_size=250M'
	 Encryption plugin parameter :  '--tmp_table_size=250M'
	 Encryption plugin parameter :  '--max_heap_table_size=250M'
	 Encryption plugin parameter :  '--max_allowed_packet=1G'
	 Encryption plugin parameter :  '--query_cache_size=0'
	 Encryption plugin parameter :  '--query_cache_type=0'
	 Encryption plugin parameter :  '--table_definition_cache=20000'
	 Encryption plugin parameter :  '--table_open_cache=20000'
	 Encryption plugin parameter :  '--wait_timeout=3600'
	 Encryption plugin parameter :  '--skip-slave-start=1'
	 Encryption plugin parameter :  '--skip-name-resolve=1'
	 Encryption plugin parameter :  '--read_only=1'
	 Encryption plugin parameter :  '--sql_mode='
	 Encryption plugin parameter :  '--ft_min_word_len=3'
	 Encryption plugin parameter :  '--ft_max_word_len=35'
	 Encryption plugin parameter :  '--gtid-domain-id=1'
	 Encryption plugin parameter :  '--gtid_strict_mode=1'
	 Encryption plugin parameter :  '--log_slave_updates=1'
	 Encryption plugin parameter :  '--relay-log-space-limit=10G'
	 Encryption plugin parameter :  '--relay_log_purge=1'
	 Encryption plugin parameter :  '--innodb_thread_concurrency=0'
	 Encryption plugin parameter :  '--innodb_flush_log_at_trx_commit=1'
	 Encryption plugin parameter :  '--loose-innodb-encryption-threads=4'
	 Encryption plugin parameter :  '--loose-innodb-encryption-rotate-key-age=1'
	 Encryption plugin parameter :  '--init_connect=SET collation_connection = utf8_unicode_ci'
	 Encryption plugin parameter :  '--init_connect=SET NAMES utf8'
	 Encryption plugin parameter :  '--character-set-server=utf8'
	 Encryption plugin parameter :  '--collation-server=utf8_unicode_ci'
	 Encryption plugin parameter :  '--skip-character-set-client-handshake'
	 Encryption plugin parameter :  '--prepare'
	 Encryption plugin parameter :  '--user=root'
	 Encryption plugin parameter :  '--password=x'
171026 22:20:58 [ERROR] mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed, 
something is definitely wrong and this may fail.

Server version: 10.2.9-MariaDB
key_buffer_size=0
read_buffer_size=131072
max_used_connections=0
max_threads=1
thread_count=0
It is possible that mysqld could use up to 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 5392 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 0x0 thread_stack 0x49000
addr2line: 'mariabackup': No such file
mariabackup(my_print_stacktrace+0x2e)[0x7f3406c8a9be]
mariabackup(handle_fatal_signal+0x30d)[0x7f340676c63d]
/lib64/libpthread.so.0(+0xf370)[0x7f3405c40370]
/lib64/libc.so.6(gsignal+0x37)[0x7f34041c91d7]
/lib64/libc.so.6(abort+0x148)[0x7f34041ca8c8]
/lib64/libc.so.6(+0x74f07)[0x7f3404208f07]
/lib64/libc.so.6(+0x7c503)[0x7f3404210503]
mariabackup(_Z30encryption_plugin_prepare_initiPPc+0x16f)[0x7f34064da14f]
mariabackup(+0x453673)[0x7f34064c2673]
mariabackup(main+0x185)[0x7f34064a1ff5]
/lib64/libc.so.6(__libc_start_main+0xf5)[0x7f34041b5b35]
mariabackup(+0x44c4ad)[0x7f34064bb4ad]
The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
information that should help you find out what is causing the crash.