LP #1658692: Missing .isl file for general tablespace from backup

**Reported in Launchpad by Shahriyar Rzayev last update 01-03-2017 07:12:36

Creating general tablespace:

mysql> create tablespace out_datadir add datafile '/home/tablespace/out_datadir.ibd';
Query OK, 0 rows affected (0.03 sec)

1. ls /var/lib/mysql | grep .isl
   out_datadir.isl

Took backup using:

/usr/bin/xtrabackup --defaults-file=/etc/my.cnf --user=root --password='Baku12345#' --target-dir=/home/backup_dir/full/2017-01-23_17-40-54 --backup --host=127.0.0.1 --port=3306 --compress=quicklz --compress-chunk-size=65536 --compress-threads=4 --encrypt=AES256 --encrypt-key='VVTBwgM4UhwkTTV98fhuj+D1zyWoA89K' --encrypt-threads=4 --encrypt-chunk-size=65536

Looking for .isl file in backup_dir:

1. ls 2017-01-23_17-40-54/
   backup-my.cnf.qp.xbcrypt fff in_datadir.ibd.qp.xbcrypt performance_schema testing xtrabackup_logfile.qp.xbcrypt
   ccc ib_buffer_pool.qp.xbcrypt mysql qptest xtrabackup_checkpoints.xbcrypt
   dbtest ibdata1.qp.xbcrypt out_datadir.ibd.qp.xbcrypt sys xtrabackup_info.qp.xbcrypt

As a result if you prepare and copy-back backup then start MySQL:

2017-01-23T13:37:14.305679Z 0 [ERROR] InnoDB: A tablespace for `out_datadir` has been found in multiple places;
2017-01-23T13:37:14.305687Z 0 [ERROR] InnoDB: Default location: ./out_datadir.ibd, Space ID=72, Flags=2048
2017-01-23T13:37:14.305691Z 0 [ERROR] InnoDB: Dictionary location: /home/tablespace/out_datadir.ibd, Space ID=72, Flags=2048
2017-01-23T13:37:14.305694Z 0 [ERROR] InnoDB: Will not open tablespace `out_datadir`
2017-01-23T13:37:14.305704Z 0 [Warning] InnoDB: Ignoring tablespace `out_datadir` because it could not be opened.
2017-01-23T13:37:14.305824Z 0 [ERROR] InnoDB: A tablespace for `out_datadir` has been found in multiple places;
2017-01-23T13:37:14.305830Z 0 [ERROR] InnoDB: Default location: ./out_datadir.ibd, Space ID=72, Flags=2048
2017-01-23T13:37:14.305833Z 0 [ERROR] InnoDB: Dictionary location: /home/tablespace/out_datadir.ibd, Space ID=72, Flags=2048
2017-01-23T13:37:14.305836Z 0 [ERROR] InnoDB: Will not open tablespace `out_datadir`
2017-01-23T13:37:14.305844Z 0 [Warning] InnoDB: Ignoring tablespace `out_datadir` because it could not be opened.

The workaround is, removing general tablespace from outside directory, then the result will be:

2017-01-23T13:38:52.083484Z 0 [ERROR] InnoDB: Operating system error number 2 in a file operation.
2017-01-23T13:38:52.083510Z 0 [ERROR] InnoDB: The error means the system cannot find the path specified.
2017-01-23T13:38:52.083513Z 0 [ERROR] InnoDB: If you are installing InnoDB, remember that you must create directories yourself, InnoDB does not create them.
2017-01-23T13:38:52.083517Z 0 [ERROR] InnoDB: Cannot open datafile for read-only: '/home/tablespace/out_datadir.ibd' OS error: 71
2017-01-23T13:38:52.089836Z 0 [Note] InnoDB: The InnoDB data dictionary table SYS_DATAFILES for tablespace ID 72 was updated to use file ./out_datadir.ibd.