Galera should pass --defaults-group-suffix to xtrabackup

[Philip Stoev]

If the my.cnf file uses sections with different suffixes, like it is under MTR, xtrabackup SST will fail because xtrabackup will not be able to find the name of the datadir and assume the datadir is . , which is not the case.

To fix this, Galera should pass the value of @@defaults-group-suffix to the xtrabackup --defaults-group= parameter.

Note however that defaults-group-suffix is a single integer whereas xtrabackup --defaults-group expects the entire string "mysqld.1"

xtrabackup --defaults-file="/home/philips/git/codership-mysql/mysql-test/var/my.cnf" --defaults-group=mysqld.1 --backup --suspend-at-end --target-dir=/tmp/tmp.Em4XWrKmVU

Until this is fixed, it is not possible to test xtrabackup SST under MTR. There is no known workaround.

[Hartmut Holzgraefe (hartmut-php)]

Unfortunately there's no defaults-group-suffix variable, the parameter value is not exposed anywhere as far as I can tell ...

[Hartmut Holzgraefe (hartmut-php)]

Also while I don't know yet how MTR handles this, at least mysqld_multi doesn't use the --default-group or --default-group-suffix option at all, it reads the suffix-specific group sections itself and then creates the mysqld command line with explicit option settings from that

e.g. with a minimalistic my.cnf like this:

  [mysqld1]
  datadir=/home/ubuntu/mariadb/data1
  server-id=1

  [mysqld2]
  datadir=/home/ubuntu/mariadb/data2
  server-id=2
  port=3307

the mysqld processes started by "mysqld_multi start" get invoked like this:

  /usr/sbin/mysqld --datadir=/home/ubuntu/mariadb/data1 --server-id=1
  /usr/sbin/mysqld --datadir=/home/ubuntu/mariadb/data2 --server-id=2 --port=3307 --socket=/tmp/mysqld2.sock

So the active datadir should rather be supplied to xtrabackup explicitly directly, instead of relying on passing the correct option file and have it picked up from there?