Although xtrabackup does not block your database’s operation, any backup
can add load to the system being backed up. On systems that do not have much
spare I/O capacity, it might be helpful to throttle the rate at which
xtrabackup reads and writes data. You can do this with the
xtrabackup --throttle option, this option limits the number of I/O
operations per second in 1 MB units.
Image below shows how throttling works when
xtrabackup --throttle is
When specified with the
xtrabackup --backup option, this option
limits the number of pairs of read-and-write operations per second that
xtrabackup will perform. If you are creating an incremental backup, then the
limit is the number of read I/O operations per second.
By default, there is no throttling, and xtrabackup reads and writes data as quickly as it can. If you set too strict of a limit on the I/O operations, the backup might be so slow that it will never catch up with the transaction logs that InnoDB is writing, so the backup might never complete.
For general inquiries about our open source software and database management tools, please send us your question and someone will contact you.