All:

I’m trying to set up regularly-scheduled backups of our MariaDB cluster with mariabackup, and have set up an account for this purpose. The account is a member of group mysql. But when I run the backup as that user:

 $   mariabackup --backup -u [myid] -p [password] mariabackup: Generating a list of tablespaces 2017-12-08 17:49:07 140352620800128 [ERROR] InnoDB: Operating system error number 13 in a file operation. 2017-12-08 17:49:07 140352620800128 [ERROR] InnoDB: The error means mysqld does not have the access rights to the directory. mariabackup: error: xb_load_tablespaces() failed witherror code 11 

If I run with sudo -u mysql, the exact same command works fine.

Is there a way to turn on extra debugging or verbosity so I can see WHICH file or directory it’s having trouble accessing?

MariaDB v10.2.11, CentOS 7 (x86_64)