Preface
ibdata1 file is a shared system tablespace of innodb engine.Although we always set variable of "innodb_file_per_table" to "on" which means put the data of table into their individual ibd files.The ibdata file will still store undo log of our innodb tables.As the ibdata1 file is inevitable to make the MySQL database running properly.Today,I'm gonna demonstrate a way to rescue the table in an instance whose ibdata file is destroied by a certain way such as write several unmeaningful characters into it.
Porcedure
Backup the instance using Xtrabackup first.
1 [root@zlm1 13:46:27 ~] 2 #innobackupex --defaults-file=/data/mysql/mysql3306/my3306.cnf --user=root --password=Passw0rd /data/backup 3 180805 13:46:40 innobackupex: Starting the backup operation 4 ... //Omitted. 5 6 [root@zlm1 13:47:14 /data/backup] 7 #ls -l 8 total 4 9 drwxr-x--- 7 root root 4096 Aug 5 13:47 2018-08-05_13-46-40 10 11 [root@zlm1 13:47:17 /data/backup]
Check the target table which we want to rescue in plan.
1 zlm@192.168.56.100:3306 [sysbench]>show tables; 2 +--------------------+ 3 | Tables_in_sysbench | 4 +--------------------+ 5 | sbtest1 | 6 | sbtest2 | 7 | sbtest3 | 8 | sbtest4 | 9 +--------------------+ 10 4 rows in set (0.00 sec) 11 12 zlm@192.168.56.100:3306 [sysbench]>select count(*) from sbtest4; 13 +----------+ 14 | count(*) | 15 +----------+ 16 | 10000 | 17 +----------+ 18 1 row in set (0.05 sec) 19 20 zlm@192.168.56.100:3306 [sysbench]>delete from sbtest4 limit 1000; 21 Query OK, 1000 rows affected (0.17 sec) 22 23 zlm@192.168.56.100:3306 [sysbench]>select count(*) from sbtest4; 24 +----------+ 25 | count(*) | 26 +----------+ 27 | 9000 | 28 +----------+ 29 1 row in set (0.00 sec)
Destroy the ibdata1 file with "dd" command.
1 [root@zlm1 13:57:01 ~] 2 #cd /data/mysql/mysql3306/data 3 4 [root@zlm1 13:59:35 /data/mysql/mysql3306/data] 5 #ls -l 6 total 433892 7 -rw-r----- 1 mysql mysql 56 Mar 18 15:10 auto.cnf 8 -rw-r----- 1 mysql mysql 81490 Aug 5 13:50 error.log 9 -rw-r----- 1 mysql mysql 882 Jul 31 16:36 ib_buffer_pool 10 -rw-r----- 1 mysql mysql 104857600 Aug 5 13:45 ibdata1 11 -rw-r----- 1 mysql mysql 104857600 Aug 5 13:45 ib_logfile0 12 -rw-r----- 1 mysql mysql 104857600 Aug 5 13:45 ib_logfile1 13 -rw-r----- 1 mysql mysql 104857600 Jul 1 14:32 ib_logfile2 14 -rw-r----- 1 mysql mysql 12582912 Aug 5 13:45 ibtmp1 15 -rw-r----- 1 mysql mysql 3924 Aug 5 13:53 innodb_status.3799 16 -rw-r----- 1 mysql mysql 0 Jul 14 02:52 innodb_status.3828 17 -rw-r----- 1 mysql mysql 4008 Jun 1 21:38 innodb_status.4131 18 drwxr-x--- 2 mysql mysql 4096 Jul 7 09:57 mrbs 19 drwxr-x--- 2 mysql mysql 4096 Mar 18 15:10 mysql 20 -rw-r----- 1 mysql mysql 5 Aug 5 13:45 mysql.pid 21 drwxr-x--- 2 mysql mysql 8192 Mar 18 15:10 performance_schema 22 -rw-r----- 1 mysql mysql 177 Jun 4 16:48 relay-bin.000001 23 -rw-r----- 1 mysql mysql 19 Jun 4 16:48 relay-bin.index 24 -rw-r----- 1 mysql mysql 526773 Aug 5 13:45 slow.log 25 drwxr-x--- 2 mysql mysql 8192 Mar 18 15:10 sys 26 drwxr-x--- 2 mysql mysql 4096 Jul 31 16:35 sysbench 27 -rw-r----- 1 mysql mysql 11610419 Jul 29 09:52 zlm1.log 28 29 [root@zlm1 13:59:38 /data/mysql/mysql3306/data] 30 #dd if=/dev/zero of=./ibdata1 bs=1024 count=262144 31 262144+0 records in 32 262144+0 records out 33 268435456 bytes (268 MB) copied, 1.61997 s, 166 MB/s 34 35 [root@zlm1 14:02:34 /data/mysql/mysql3306/data] 36 #ls -l|grep ibdata1 37 -rw-r----- 1 mysql mysql 268435456 Aug 5 14:06 ibdata1 //The ibdata1 turned out to be 256M and filled with zero.
Restart the MySQL instance.
1 zlm@192.168.56.100:3306 [sysbench]>exit 2 Bye 3 4 [root@zlm1 14:13:06 ~] 5 #mysqladmin shutdown 6 7 [root@zlm1 14:13:10 ~] 8 #ps aux|grep mysqld 9 root 4002 0.0 0.0 112640 960 pts/0 R+ 14:13 0:00 grep --color=auto mysqld 10 11 [root@zlm1 14:13:15 ~] 12 #./mysqld.sh 13 14 [root@zlm1 14:13:53 ~] 15 #mysql 16 ERROR 2003 (HY000): Can't connect to MySQL server on '192.168.56.100' (111) 17 18 [root@zlm1 14:13:56 ~] 19 #mysql 20 ERROR 2003 (HY000): Can't connect to MySQL server on '192.168.56.100' (111) 21 22 [root@zlm1 14:13:58 ~] 23 #cd /data/mysql/mysql3306/data 24 25 [root@zlm1 14:14:07 /data/mysql/mysql3306/data] 26 #tail error.log 27 ... /Omitted. 28 2018-08-05T12:13:53.242723Z 0 [Note] --secure-file-priv is set to NULL. Operations related to importing and exporting data are disabled 29 2018-08-05T12:13:53.242806Z 0 [Note] mysqld (mysqld 5.7.21-log) starting as process 4008 ... 30 2018-08-05T12:13:53.249168Z 0 [Note] InnoDB: PUNCH HOLE support available 31 2018-08-05T12:13:53.249207Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins 32 2018-08-05T12:13:53.249213Z 0 [Note] InnoDB: Uses event mutexes 33 2018-08-05T12:13:53.249218Z 0 [Note] InnoDB: GCC builtin __sync_synchronize() is used for memory barrier 34 2018-08-05T12:13:53.249222Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.3 35 2018-08-05T12:13:53.249227Z 0 [Note] InnoDB: Using Linux native AIO 36 2018-08-05T12:13:53.249426Z 0 [Note] InnoDB: Number of pools: 1 37 2018-08-05T12:13:53.249507Z 0 [Note] InnoDB: Using CPU crc32 instructions 38 2018-08-05T12:13:53.251488Z 0 [Note] InnoDB: Initializing buffer pool, total size = 100M, instances = 1, chunk size = 100M 39 2018-08-05T12:13:53.256630Z 0 [Note] InnoDB: Completed initialization of buffer pool 40 2018-08-05T12:13:53.257913Z 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority(). 41 2018-08-05T12:13:53.280321Z 0 [Note] InnoDB: Highest supported file format is Barracuda. 42 12:13:53 UTC - mysqld got signal 11 ; 43 This could be because you hit a bug. It is also possible that this binary 44 or one of the libraries it was linked against is corrupt, improperly built, 45 or misconfigured. This error can also be caused by malfunctioning hardware. 46 Attempting to collect some information that could help diagnose the problem. 47 As this is a crash and something is definitely wrong, the information 48 collection process might fail. 49 50 key_buffer_size=8388608 51 read_buffer_size=2097152 52 max_used_connections=0 53 max_threads=100 54 thread_count=0 55 connection_count=0 56 It is possible that mysqld could use up to 57 key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 227127 K bytes of memory 58 Hope that's ok; if not, decrease some variables in the equation. 59 60 Thread pointer: 0x0 61 Attempting backtrace. You can use the following information to find out 62 where mysqld died. If you see no messages after this, something went 63 terribly wrong... 64 stack_bottom = 0 thread_stack 0x30000 65 mysqld(my_print_stacktrace+0x35)[0xf4a495] 66 mysqld(handle_fatal_signal+0x4a4)[0x7ce2f4] 67 /lib64/libpthread.so.0(+0xf130)[0x7f6bbee76130] 68 mysqld(_Z26page_cur_search_with_matchPK11buf_block_tPK12dict_index_tPK8dtuple_t15page_cur_mode_tPmS9_P10page_cur_tP8rtr_info+0x148)[0x1074478] 69 mysqld(_Z27btr_cur_search_to_nth_levelP12dict_index_tmPK8dtuple_t15page_cur_mode_tmP9btr_cur_tmPKcmP5mtr_t+0x1598)[0x11806d8] 70 mysqld(_Z30btr_pcur_open_on_user_rec_funcP12dict_index_tPK8dtuple_t15page_cur_mode_tmP10btr_pcur_tPKcmP5mtr_t+0x212)[0x1184b62] 71 mysqld[0x11df28d] 72 mysqld(_Z19dict_load_sys_tableP12dict_table_t+0x69)[0x11e0609] 73 mysqld(_Z9dict_bootv+0xdfb)[0x11bf48b] 74 mysqld(_Z34innobase_start_or_create_for_mysqlv+0x3212)[0x11150a2] 75 mysqld[0x100023a] 76 mysqld(_Z24ha_initialize_handlertonP13st_plugin_int+0x51)[0x819721] 77 mysqld[0xd39226] 78 mysqld(_Z40plugin_register_builtin_and_init_core_sePiPPc+0x3e4)[0xd397a4] 79 mysqld[0x7c48f7] 80 mysqld(_Z11mysqld_mainiPPc+0x92f)[0x7c7e9f] 81 /lib64/libc.so.6(__libc_start_main+0xf5)[0x7f6bbd857af5] 82 mysqld[0x7be479] 83 The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains 84 information that should help you find out what is causing the crash. 85 86 [root@zlm1 14:14:36 /data/mysql/mysql3306/data] 87 88 //Okay,becasue of the lack of normal ibdata1 file in datadir,the instance cannot be started again. 89 //Then,how can we resuce the data in target table 'sbtest4'? 90 //First of all,let's get the ibd and frm file of it from the crashed server.
Copy ibd and frm file of table "sbtest4" to another newly initialized instance on zlm2.
1 [root@zlm1 14:20:39 /data/mysql/mysql3306/data/sysbench] 2 #scp sbtest4.* zlm2:/data/backup 3 sbtest4.frm 100% 8632 8.4KB/s 00:00 4 sbtest4.ibd 100% 10MB 10.0MB/s 00:01
Install mysql-utilities package on zlm2.
1 [root@zlm2 14:23:13 ~] 2 #mysqlfrm --help 3 -bash: mysqlfrm: command not found 4 5 [root@zlm2 14:23:17 ~] 6 #yum install mysql-utilities 7 Loaded plugins: fastestmirror 8 base | 3.6 kB 00:00:00 9 epel/x86_64/metalink | 7.0 kB 00:00:00 10 epel | 3.2 kB 00:00:00 11 extras | 3.4 kB 00:00:00 12 updates | 3.4 kB 00:00:00 13 (1/5): epel/x86_64/group_gz | 88 kB 00:00:00 14 (2/5): epel/x86_64/updateinfo | 932 kB 00:00:00 15 (3/5): extras/7/x86_64/primary_db | 173 kB 00:00:00 16 (4/5): epel/x86_64/primary | 3.6 MB 00:00:01 17 (5/5): updates/7/x86_64/primary_db | 4.3 MB 00:00:04 18 Loading mirror speeds from cached hostfile 19 * base: mirrors.shu.edu.cn 20 * epel: mirrors.tongji.edu.cn 21 * extras: mirrors.163.com 22 * updates: mirrors.163.com 23 epel 12629/12629 24 Resolving Dependencies 25 --> Running transaction check 26 ---> Package mysql-utilities.noarch 0:1.3.6-1.el7 will be installed 27 --> Processing Dependency: mysql-connector-python for package: mysql-utilities-1.3.6-1.el7.noarch 28 --> Running transaction check 29 ---> Package mysql-connector-python.noarch 0:1.1.6-1.el7 will be installed 30 --> Finished Dependency Resolution 31 32 ... //Omitted. 33 34 Installed: 35 mysql-utilities.noarch 0:1.3.6-1.el7 36 37 Dependency Installed: 38 mysql-connector-python.noarch 0:1.1.6-1.el7 39 40 Complete!
Restore the table structure by mysqlfrm.
1 [root@zlm2 14:30:41 ~] 2 #cd /data/backup/ 3 4 [root@zlm2 14:30:48 /data/backup] 5 #ls -l|grep sbtest4 6 -rw-r----- 1 root root 8632 Aug 5 14:30 sbtest4.frm 7 -rw-r----- 1 root root 10485760 Aug 5 14:30 sbtest4.ibd 8 9 [root@zlm2 14:31:25 /data/backup] 10 #mysqlfrm --basedir=/usr/local/mysql --port=8219 --diagnostic ./sbtest4.frm 11 # WARNING The --port option is not used in the --diagnostic mode. 12 # WARNING: Cannot generate character set or collation names without the --server option. 13 # CAUTION: The diagnostic mode is a best-effort parse of the .frm file. As such, it may not identify all of the components of the table correctly. This is especially true for damaged files. It will also not read the default values for the columns and the resulting statement may not be syntactically correct. 14 # Reading .frm file for ./sbtest4.frm: 15 # The .frm file is a TABLE. 16 # CREATE TABLE Statement: 17 18 CREATE TABLE `sbtest4` ( 19 `id` int(11) NOT NULL AUTO_INCREMENT, 20 `k` int(11) NOT NULL, 21 `c` char(360) NOT NULL, 22 `pad` char(180) NOT NULL, 23 PRIMARY KEY `PRIMARY` (`id`), 24 KEY `k_4` (`k`) 25 ) ENGINE=InnoDB; 26 27 #...done.
Create a same table structure in the new instance using the restored "create table" statement.
1 [root@zlm2 14:39:02 /data/backup] 2 #mysql 3 Welcome to the MySQL monitor. Commands end with ; or g. 4 Your MySQL connection id is 7 5 Server version: 5.7.21-log MySQL Community Server (GPL) 6 7 Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. 8 9 Oracle is a registered trademark of Oracle Corporation and/or its 10 affiliates. Other names may be trademarks of their respective 11 owners. 12 13 Type 'help;' or 'h' for help. Type 'c' to clear the current input statement. 14 15 zlm@192.168.56.101:3306 [(none)]>show databases; 16 +--------------------+ 17 | Database | 18 +--------------------+ 19 | information_schema | 20 | mrbs | 21 | mysql | 22 | performance_schema | 23 | sys | 24 +--------------------+ 25 5 rows in set (0.00 sec) 26 27 zlm@192.168.56.101:3306 [(none)]>create database sysbench; 28 Query OK, 1 row affected (0.00 sec) 29 30 zlm@192.168.56.101:3306 [(none)]>use sysbench 31 Database changed 32 zlm@192.168.56.101:3306 [sysbench]>show tables; 33 Empty set (0.00 sec) 34 35 zlm@192.168.56.101:3306 [sysbench]>CREATE TABLE `sbtest4` ( 36 -> `id` int(11) NOT NULL AUTO_INCREMENT, 37 -> `k` int(11) NOT NULL, 38 -> `c` char(360) NOT NULL, 39 -> `pad` char(180) NOT NULL, 40 -> PRIMARY KEY `PRIMARY` (`id`), 41 -> KEY `k_4` (`k`) 42 -> ) ENGINE=InnoDB; 43 ERROR 1074 (42000): Column length too big for column 'c' (max = 255); use BLOB or TEXT instead 44 zlm@192.168.56.101:3306 [sysbench]>CREATE TABLE `sbtest4` ( 45 -> `id` int(11) NOT NULL AUTO_INCREMENT, 46 -> `k` int(11) NOT NULL, 47 -> `c` char(120) NOT NULL, 48 -> `pad` char(60) NOT NULL, 49 -> PRIMARY KEY `PRIMARY` (`id`), 50 -> KEY `k_4` (`k`) 51 -> ) ENGINE=InnoDB; 52 ERROR 1146 (42S02): Table 'sysbench.sbtest4' doesn't exist 53 zlm@192.168.56.101:3306 [sysbench]>CREATE TABLE `sbtest4_bak` ( 54 -> `id` int(11) NOT NULL AUTO_INCREMENT, 55 -> `k` int(11) NOT NULL, 56 -> `c` char(120) NOT NULL, 57 -> `pad` char(60) NOT NULL, 58 -> PRIMARY KEY `PRIMARY` (`id`), 59 -> KEY `k_4` (`k`) 60 -> ) ENGINE=InnoDB; 61 Query OK, 0 rows affected (0.01 sec) 62 63 64 zlm@192.168.56.101:3306 [sysbench]>rename table sbtest4_bak to sbtest4; 65 Query OK, 0 rows affected (0.00 sec) 66 67 zlm@192.168.56.101:3306 [sysbench]>show tables; 68 +--------------------+ 69 | Tables_in_sysbench | 70 +--------------------+ 71 | sbtest4 | 72 +--------------------+ 73 1 row in set (0.00 sec) 74 75 zlm@192.168.56.101:3306 [sysbench]>show create table sbtest4G 76 *************************** 1. row *************************** 77 Table: sbtest4 78 Create Table: CREATE TABLE `sbtest4` ( 79 `id` int(11) NOT NULL AUTO_INCREMENT, 80 `k` int(11) NOT NULL, 81 `c` char(120) NOT NULL, 82 `pad` char(60) NOT NULL, 83 PRIMARY KEY (`id`), 84 KEY `k_4` (`k`) 85 ) ENGINE=InnoDB DEFAULT CHARSET=utf8 86 1 row in set (0.00 sec) 87 88 zlm@192.168.56.101:3306 [sysbench]>select count(*) from sbtest4; 89 +----------+ 90 | count(*) | 91 +----------+ 92 | 0 | 93 +----------+ 94 1 row in set (0.00 sec)
Discard the tablesapce of new table "sbtest4".
1 zlm@192.168.56.101:3306 [sysbench]>alter table sbtest4 discard tablespace; 2 Query OK, 0 rows affected (0.00 sec) 3 4 [root@zlm2 15:01:45 /data/mysql/mysql3306/data/sysbench] 5 #ls -l 6 total 16 7 -rw-r----- 1 mysql mysql 61 Aug 5 14:39 db.opt 8 -rw-r----- 1 mysql mysql 8632 Aug 5 14:54 sbtest4.frm 9 10 //After the discard operation,the new ibd file has gone.
Copy the ibd file of table "sbtest4" to the sysbench directory in datadir(notice the owner of file).
1 [root@zlm2 15:05:42 /data/backup] 2 #cp sbtest4.ibd /data/mysql/mysql3306/data/sysbench/ 3 4 [root@zlm2 15:05:54 /data/backup] 5 #ll /data/mysql/mysql3306/data/sysbench/ |grep sbtest4 6 -rw-r----- 1 mysql mysql 8632 Aug 5 14:54 sbtest4.frm 7 -rw-r----- 1 root root 10485760 Aug 5 15:05 sbtest4.ibd 8 9 [root@zlm2 15:06:12 /data/backup] 10 #chown mysql.mysql /data/mysql/mysql3306/data/sysbench/sbtest4.ibd 11 12 [root@zlm2 15:06:39 /data/backup] 13 #ll /data/mysql/mysql3306/data/sysbench/ |grep sbtest4 14 -rw-r----- 1 mysql mysql 8632 Aug 5 14:54 sbtest4.frm 15 -rw-r----- 1 mysql mysql 10485760 Aug 5 15:05 sbtest4.ibd
Import the original tablespace of table "sbtest4".
1 zlm@192.168.56.101:3306 [sysbench]>alter table sbtest4 import tablespace; 2 Query OK, 0 rows affected, 1 warning (1.77 sec) 3 4 zlm@192.168.56.101:3306 [sysbench]>select count(*) from sbtest4; 5 +----------+ 6 | count(*) | 7 +----------+ 8 | 9000 | 9 +----------+ 10 1 row in set (0.01 sec) 11 12 //Now the table has been rescued. 13 //Because of the destroying of ibdata1 in the original instance,it should be restored by Xtrabackup again.
Summary
- This method is only used to resuce a single table without backup when MySQL instance cannot startup beause of the destoryed ibdata file.
- mysqlfrm is a tool which can load table structure from .frm files.We need to install the mysql-utilities package first.
- If we don't have a properly full Xtrabackup and binlog，the .ibd file may lose the undo information on target table.In this situation,it's an incompletely recovery.