How does Live Transfer handle database synchronization?

[citizen8601]

When using the Live Transfer feature of the Transfer Tool, I would like to know more than the documentation gives about how MySQL databases are synchronized between the source and destination servers. During the transfer, the source server continues serving the website until it is set to proxy requests to the destination server. Do I need to assume that database updates that are made after (or while) the database is transferred but before proxying begins will never be reflected on the destination server? And if so, how can I find out how long that window is? Is there a final sync of the database after a complete initial transfer is done? Looking at the transfer logs, it doesn't look to me like there is.

My source and destination servers are both cPanel v98.0.10.

 

[andrew.n]

Access to the databases is not being "forwarded" after the live transfer. Only http/https requests will be forwarded to the destination server. I believe the live transfer adjust the DNS records only when the extraction and the restoration of the account is being done on the destination server (as the last step of the transfer) however I hope @cPRex can confirm this as I'm not 100% sure.

 

[cPRex]

I think @cPanelAnthony is doing some homework on this and will post an update soon.

 

[cPanelAnthony]

Hello! The transfer uses a web socket. The following article might help.

The MysqlDump Stream | cPanel & WHM Documentation

The MysqlDump stream allows you to produce a dump of a MySQL® database via WebSocket.

docs.cpanel.net

There wouldn't be a final sync during the live transfer process. Regarding the details about how long the database transfer process works, if it's logged, etc... I am conferring with my team now. I will update this thread as soon as possible.

 

[cPanelAnthony]

Hello again! I have confirmed that as far as live transfers go, there are unfortunately no checks to ensure the database data is up to date after the transfer. The goal was to improve the synchronization with streaming, but there's always going to be some risk of data loss. That chance is lesser now that streaming and proxying are used. I apologize for any inconvenience.

 

[citizen8601]

@cPanelAnthony, thank you for your thorough answer. This is very helpful for strategizing site transfers. Live Transfer is a great feature; I just needed to understand the implications.