* The node is far behind and binary log sync would take long time.
* Binary logs are not available to sync
Recipient: Server instance, where the clone statement is executed.
Donor: The source server instance from which the data is going to be cloned. The Donor collects all its data and metadata stored in the InnoDB storage engine at a consistent snapshot to replace the data in Recipient.
After successful execution of a CLONE SQL statement the Recipient server is restarted automatically. The restart involves recovery. Once restarted, recipient is a clone of donor server!
Donor dynamic snapshot is transferred in three stages.
File Copy
Page Copy
Redo Copy
Recipient: Server instance, where the clone statement is executed.
Donor: The source server instance from which the data is going to be cloned. The Donor collects all its data and metadata stored in the InnoDB storage engine at a consistent snapshot to replace the data in Recipient.
After successful execution of a CLONE SQL statement the Recipient server is restarted automatically. The restart involves recovery. Once restarted, recipient is a clone of donor server!
One or zero rows
ID
A unique cloning operation identifier in the current MySQL server instance.
PID
Process list ID of the session executing the cloning operation.
STATE
Current state of the cloning operation. Values include Not Started, In Progress, Completed, and Failed.
BEGIN_TIME
A timestamp in 'YYYY-MM-DD hh:mm:ss[.fraction]' format that shows when the cloning operation started.
END_TIME
A timestamp in 'YYYY-MM-DD hh:mm:ss[.fraction]' format that shows when the cloning operation finished. Reports NULL if the operation has not ended.
SOURCE
The donor MySQL server address in 'HOST:PORT' format. The column displays 'LOCAL INSTANCE' for a local cloning operation.
DESTINATION
The directory being cloned to.
ERROR_NO
The error number reported for a failed cloning operation.
ERROR_MESSAGE
The error message string for a failed cloning operation.
BINLOG_FILE
The name of the binary log file up to which data is cloned.
BINLOG_POSITION
The binary log file offset up to which data is cloned.
GTID_EXECUTED
The GTID value for the last cloned transaction.
ID
A unique cloning operation identifier in the current MySQL server instance.
STAGE
The name of the current cloning stage. Stages include DROP DATA, FILE COPY, PAGE_COPY, REDO_COPY, FILE_SYNC, RESTART, and RECOVERY.
STATE
The current state of the cloning stage. States include Not Started, In Progress, and Completed.
BEGIN_TIME
A timestamp in 'YYYY-MM-DD hh:mm:ss[.fraction]' format that shows when the cloning stage started. Reports NULL if the stage has not started.
END_TIME
A timestamp in 'YYYY-MM-DD hh:mm:ss[.fraction]' format that shows when the cloning stage finished. Reports NULL if the stage has not ended.
THREADS
The number of concurrent threads used in the stage.
ESTIMATE
The estimated amount of data for the current stage, in bytes.
DATA
The amount of data transferred in current state, in bytes.
NETWORK
The amount of network data transferred in the current state, in bytes.
DATA_SPEED
The current actual speed of data transfer, in bytes per second. This value may differ from the requested maximum data transfer rate defined by clone_max_data_bandwidth.
NETWORK_SPEED
The current speed of network transfer in bytes per second.
Clone plugin uses multiple connections from recipient to donor server.
- clone_max_concurrency limits maximum connections
Clone operation starts with 1 connection thread and threads are increased in steps. Auto tuning checks and stop spawning new connections if no significant performance improvement is noticed.
- clone_autotune_concurrency
If cpu, i/o, Network resource is saturated then increasing connections/threads could degrade performance and could also impact donor performance. Auto tuning helps here.