MySQL 5.7 doesn’t start after installation on CentOS 6.7

The cause for the problem was most likely an HDD error, while MySQL was writing in table "xyz". Finally I was able to recover the system. Here is what I did:

1. Data Backup including MySQL datadir (table "xyz" and my "ibdata" could be read/copied, so no complete backup possible) Ran chkdsk —> found but didn’t repair bad sectors
2. ran HDD Regenerator v2011 —> found and repaired bad sectors
3. Completed Backup
4. Tested if MySQL would run after regeneration —> didn’t work
5. added innodb_force_recovery=1 … 6 to [mysqld] section in my config file (MySQL started only with max value "6")
6. used mysqlcheck db_name -u root -p to check which table(s) are corrupted
7. used mysqluc > mysqlfrm to obtain the table structure of the corrupted table (worked only with --diagnostic option)
8. used myisamchk -r -q table_name to fix the broken table (this table used the myisam engine)
9. see this: http://dev.mysql.com/doc/refman/5.7/en/myisam-repair.html
10. I had to use this trick to get it working: FOR %G IN (dir \b c:\mysql\data\mydb\*.myi) DO myisamchk -r -f %G (https://iandunn.name/myisamchk-error-22-on-windows/)
11. Originally the table had 55721190 rows, after myisamchk repair it had 55721166 rows (no problem for me, because i could identify and restore the lost rows)
12. Backup
13. mysqldump -u root -p my_schema > .../recovery_dump.sql
14. mysql drop all_databases, stopped server, moved ibdata1 and iblogs to tmp folder, deleted innodb_force_recovery=6 in config file, started server
15. mysql -u root -p my_schema < .../recovery_dump.sql

This "InnoDB Corruption Repair Guide" was a great help. (https://forums.cpanel.net/threads/innodb-corruption-repair-guide.418722/)

I keep seeing permission denied errors in the log.

You didn't run the chown command recursively

Please do this

chown -R mysql:mysql ./path/to/rh-mysql56

I also see errors like

2016-06-30 14:14:48 9138 [ERROR] InnoDB: Tablespace open failed for '"mysql"."innodb_index_stats"', ignored.

When you installed mysql before, it created 5 InnoDB system tables (See my answers Cannot open table mysql/innodb_index_stats and InnoDB: Error: Table "mysql"."innodb_table_stats" not found after upgrade to mysql 5.6).

You need to recreate them.

First you need to delete the orphaned .frm files

cd ./path/to/rh-mysql56/mysql
rm -f innodb_index_stats.frm
rm -f innodb_table_stats.frm
rm -f slave_master_info.frm
rm -f slave_relay_log_info.frm
rm -f slave_worker_info.frm
rm -f innodb_index_stats.ibd
rm -f innodb_table_stats.ibd
rm -f slave_master_info.ibd
rm -f slave_relay_log_info.ibd
rm -f slave_worker_info.ibd

Then, you can recreate them with

USE mysql
CREATE TABLE `innodb_index_stats` (
  `database_name` varchar(64) COLLATE utf8_bin NOT NULL,
  `table_name` varchar(64) COLLATE utf8_bin NOT NULL,
  `index_name` varchar(64) COLLATE utf8_bin NOT NULL,
  `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `stat_name` varchar(64) COLLATE utf8_bin NOT NULL,
  `stat_value` bigint(20) unsigned NOT NULL,
  `sample_size` bigint(20) unsigned DEFAULT NULL,
  `stat_description` varchar(1024) COLLATE utf8_bin NOT NULL,
  PRIMARY KEY (`database_name`,`table_name`,`index_name`,`stat_name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin STATS_PERSISTENT=0;
CREATE TABLE `innodb_table_stats` (
  `database_name` varchar(64) COLLATE utf8_bin NOT NULL,
  `table_name` varchar(64) COLLATE utf8_bin NOT NULL,
  `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `n_rows` bigint(20) unsigned NOT NULL,
  `clustered_index_size` bigint(20) unsigned NOT NULL,
  `sum_of_other_index_sizes` bigint(20) unsigned NOT NULL,
  PRIMARY KEY (`database_name`,`table_name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin STATS_PERSISTENT=0;
CREATE TABLE `slave_master_info` (
  `Number_of_lines` int(10) unsigned NOT NULL COMMENT 'Number of lines in the file.',
  `Master_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL COMMENT 'The name of the master binary log currently being read from the master.',
  `Master_log_pos` bigint(20) unsigned NOT NULL COMMENT 'The master log position of the last read event.',
  `Host` char(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL DEFAULT '' COMMENT 'The host name of the master.',
  `User_name` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The user name used to connect to the master.',
  `User_password` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The password used to connect to the master.',
  `Port` int(10) unsigned NOT NULL COMMENT 'The network port used to connect to the master.',
  `Connect_retry` int(10) unsigned NOT NULL COMMENT 'The period (in seconds) that the slave will wait before trying to reconnect to the master.',
  `Enabled_ssl` tinyint(1) NOT NULL COMMENT 'Indicates whether the server supports SSL connections.',
  `Ssl_ca` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The file used for the Certificate Authority (CA) certificate.',
  `Ssl_capath` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The path to the Certificate Authority (CA) certificates.',
  `Ssl_cert` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The name of the SSL certificate file.',
  `Ssl_cipher` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The name of the cipher in use for the SSL connection.',
  `Ssl_key` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The name of the SSL key file.',
  `Ssl_verify_server_cert` tinyint(1) NOT NULL COMMENT 'Whether to verify the server certificate.',
  `Heartbeat` float NOT NULL,
  `Bind` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'Displays which interface is employed when connecting to the MySQL server',
  `Ignored_server_ids` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The number of server IDs to be ignored, followed by the actual server IDs',
  `Uuid` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The master server uuid.',
  `Retry_count` bigint(20) unsigned NOT NULL COMMENT 'Number of reconnect attempts, to the master, before giving up.',
  `Ssl_crl` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The file used for the Certificate Revocation List (CRL)',
  `Ssl_crlpath` text CHARACTER SET utf8 COLLATE utf8_bin COMMENT 'The path used for Certificate Revocation List (CRL) files',
  `Enabled_auto_position` tinyint(1) NOT NULL COMMENT 'Indicates whether GTIDs will be used to retrieve events from the master.',
  PRIMARY KEY (`Host`,`Port`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 STATS_PERSISTENT=0 COMMENT='Master Information';
CREATE TABLE `slave_relay_log_info` (
  `Number_of_lines` int(10) unsigned NOT NULL COMMENT 'Number of lines in the file or rows in the table. Used to version table definitions.',
  `Relay_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL COMMENT 'The name of the current relay log file.',
  `Relay_log_pos` bigint(20) unsigned NOT NULL COMMENT 'The relay log position of the last executed event.',
  `Master_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL COMMENT 'The name of the master binary log file from which the events in the relay log file were read.',
  `Master_log_pos` bigint(20) unsigned NOT NULL COMMENT 'The master log position of the last executed event.',
  `Sql_delay` int(11) NOT NULL COMMENT 'The number of seconds that the slave must lag behind the master.',
  `Number_of_workers` int(10) unsigned NOT NULL,
  `Id` int(10) unsigned NOT NULL COMMENT 'Internal Id that uniquely identifies this record.',
  PRIMARY KEY (`Id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 STATS_PERSISTENT=0 COMMENT='Relay Log Information';
CREATE TABLE `slave_worker_info` (
  `Id` int(10) unsigned NOT NULL,
  `Relay_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `Relay_log_pos` bigint(20) unsigned NOT NULL,
  `Master_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `Master_log_pos` bigint(20) unsigned NOT NULL,
  `Checkpoint_relay_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `Checkpoint_relay_log_pos` bigint(20) unsigned NOT NULL,
  `Checkpoint_master_log_name` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `Checkpoint_master_log_pos` bigint(20) unsigned NOT NULL,
  `Checkpoint_seqno` int(10) unsigned NOT NULL,
  `Checkpoint_group_size` int(10) unsigned NOT NULL,
  `Checkpoint_group_bitmap` blob NOT NULL,
  PRIMARY KEY (`Id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 STATS_PERSISTENT=0 COMMENT='Worker Information';