switch more datadir

[biagio rea]

on my development PC
I wish I had more than one datadir to switch by datadir param in mysql configuration file

on windows-wamp I get the target easily
just make several copies of the original data\ folder
eg
D:\db\data1\
D:\db\data2\
D:\db\data3\
switch datadir da my.ini and restart mysqld service

on linuxubuntu I get error
I've done copies of the original folder, keeping permissions and owner
/var/lib/mysql1/
/var/lib/mysql2/
/var/lib/mysql3/
switch datadir by my.cnf, and restart mysqld service


$ sudo service mysql start
start: Job failed to start

/var/log/mysql/error.log

2016-04-10 17:25:38 3655 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
2016-04-10 17:25:38 3655 [Note] Plugin 'FEDERATED' is disabled.
/usr/sbin/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13 - Permission denied)
2016-04-10 17:25:38 3655 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
2016-04-10 17:25:38 3655 [Note] InnoDB: Using atomics to ref count buffer pool pages
2016-04-10 17:25:38 3655 [Note] InnoDB: The InnoDB memory heap is disabled
2016-04-10 17:25:38 3655 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2016-04-10 17:25:38 3655 [Note] InnoDB: Memory barrier is not used
2016-04-10 17:25:38 3655 [Note] InnoDB: Compressed tables use zlib 1.2.8
2016-04-10 17:25:38 3655 [Note] InnoDB: Using Linux native AIO
2016-04-10 17:25:38 3655 [Note] InnoDB: Using CPU crc32 instructions
2016-04-10 17:25:38 3655 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2016-04-10 17:25:38 3655 [Note] InnoDB: Completed initialization of buffer pool
2016-04-10 17:25:38 3655 [ERROR] InnoDB: ./ibdata1 can't be opened in read-write mode
2016-04-10 17:25:38 3655 [ERROR] InnoDB: The system tablespace must be writable!
2016-04-10 17:25:38 3655 [ERROR] Plugin 'InnoDB' init function returned error.
2016-04-10 17:25:38 3655 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2016-04-10 17:25:38 3655 [ERROR] Unknown/unsupported storage engine: InnoDB
2016-04-10 17:25:38 3655 [ERROR] Aborting

thanks from now for the suggestions