Comment 1 for bug 1257470

This is similar to other hard-coded defaults in the server, though this one is specific to single binary implementation. For example, if there's no explicit datadir in my.cnf, the server will use a default value that depends on whether it was installed from .tar.gz, or Debian package, or RPM. XtraBackup has no way to guess this default, so it will fail.

It is the same case here: innodb_log_file_size is an essential part of InnoDB configuration for XtraBackup, but if it's not specifiied explicitly, there's no reliable way to guess the default value used by the server. This can be implemented in a reliable way when we merged innobackupex and xtrabackup.

For now, we should document it as a known limitation. Added a note to https://blueprints.launchpad.net/percona-xtrabackup/+spec/document-single-binary