Mysql doesn´t start after expending data-dir with simlink to another database

Question

I´ve installed mysql and it worked fine.

Now I´d liked to have the data of several databases in my dropbox. So I put symlinks in my mysql data dir.

sudo ln -s /Users/michaelbenker/Dropbox/geschaeft/softwareentwicklung/DB/testdatabase /usr/local/mysql/data/testdatabase

Now when I tried to restart mysql, I get the error

ERROR! MySQL server PID file could not be found!
Starting MySQL
. ERROR! The server quit without updating PID file 
(/usr/local/mysql/data/Michaels-iMac-783.local.pid).

In my error file I found this entry

2017-05-26T11:29:12.067923Z 0 [ERROR] InnoDB: Operating system error 
number 13 in a file operation.
2017-05-26T11:29:12.067928Z 0 [ERROR] InnoDB: The error means mysqld 
does not have the access rights to the directory.
2017-05-26T11:29:12.067934Z 0 [ERROR] InnoDB: 
os_file_readdir_next_file() returned -1 in directory ./, crash recovery 
may have failed for some .ibd files!
2017-05-26T11:29:12.067963Z 0 [ERROR] InnoDB: Plugin initialization 
aborted with error Generic error
2017-05-26T11:29:12.375057Z 0 [ERROR] Plugin 'InnoDB' init function 
returned error.
2017-05-26T11:29:12.375090Z 0 [ERROR] Plugin 'InnoDB' registration as a 
STORAGE ENGINE failed.
2017-05-26T11:29:12.375097Z 0 [ERROR] Failed to initialize plugins.
2017-05-26T11:29:12.375100Z 0 [ERROR] Aborting

So I tried several things to change the permission to my Dropbox data-dir

• I tried to change the owner to mysql (tried also _mysql)
• I tried to change the group to mysql (tried also _mysql)
• I tried to change the chmod to 777

Nothing helped.

I did the same on my MacBook and here everything worked fine.

Here the actual permissions on the Dropbox Dir

drwxrwxrwx@  5 _mysql         _mysql    170 26 Mai 13:02 DB

Answer 1

MySQL will also need to be able to change into the parents of the Dropbox directory, which implies a +x on each one.