Testing Remote Backup Capability of MySQL Enterprise Backup (mysqlbackup) 4.0

Background – The author encountered an interesting situation at a client site where the mysqlbackup tool appeared to support remote backups, which the official documentation states it does not.

Test Environment – Two servers (A and B) each run a MySQL 5.7.25 instance on port 3306. Backup users user_A@'%' (password_A) and user_B@'%' (password_B) were created, with test databases a1‑a3 on A and b1‑b3 on B. Both servers use MySQL Enterprise Backup version 4.0.0.

Backup Command – The simplest physical backup command used was:

shell> mysqlbackup --defaults-file=/opt/mysql/etc/3306/my.cnf --user=user_A --password=password_A --host=10.186.64.13 --backup-dir=/data/backup01 backup

Test Scenario 1: Local Backup of MySQL A on Server A

Backup succeeded while MySQL A was running (hot backup).

Backup failed when MySQL A was stopped.

Using an incorrect password also caused failure.

Test Scenario 2: Remote Backup of MySQL B from Server A

When MySQL B was running, the remote backup succeeded regardless of MySQL A’s state, but the data backed up were actually the local databases a1‑a3.

When MySQL B was stopped, the remote backup always failed.

Test Results – With the correct user/password and a running remote instance, mysqlbackup can connect to the remote server and perform a backup, but the backup still contains the local instance’s data. The tool cannot back up a stopped instance.

Further Investigation – The official documentation describes the --host option as a compatibility flag that does not affect the connection, yet the test showed successful remote authentication. Switching to mysqlbackup 4.1.4 revealed that the --host option is ignored and the tool forces a local socket connection, requiring a localhost user.

Conclusion – MySQL Enterprise Backup 4.0 can mistakenly back up local data when the --host option points to a remote server, but versions 4.1 and later enforce local socket connections, making true remote physical backups impossible.

Correction – The screenshots mistakenly show the command mysqlback ; the correct command is mysqlbackup .